1 Wittkower, Rudolf, ‘Michelangelo's Biblioteca Laurenziana’, The Art Bulletin, 16 (1934), pp. 123–218 CrossRefGoogle Scholar; republished in Idea and Image (London, 1978), pp. 11–71 Google ScholarPubMed. References here are made to the 1978 publication.

2 Wittkower, ‘Biblioteca Laurenziana’, p. 11.

3 This trend was due to the wide acceptance of Wittkower's analysis of the drawings. A notable exception is David Hemsoll, who suggests many precedents that may have influenced Michelangelo's designs for the façade project, the Medici Chapel, and the Laurentian Library at S. Lorenzo. See Hemsoll, David, ‘The Laurentian Library and Michelangelo's Architectural Method’, Journal of the Warburg and Courtauld Institute, LXVI (2003), pp. 29–62 Google Scholar.

4 This is true for most of Michelangelo's architectural projects: while scholars generally consider various graphic and literary sources, it is difficult to glean an understanding of the design evolution of a particular design. Therefore, it is not surprising that the primary focus of most scholarship has been on the works as built. However, complete understanding of the extent buildings also continues to elude us because every work is incomplete and consequently does not fully reflect Michelangelo's design intentions. Each project was either abandoned by Michelangelo and left incomplete, or was partially continued or completed by others. In each case, in order to understand his designs, it is necessary to examine the buildings as built in conjunction with surviving documentation of unrealized intentions. It is impossible to say how Michelangelo would have definitively finished any of his architectural projects because no complete design drawings survive.

5 Vasari, Giorgio, Lives of the Painters, Sculptors and Architects (New York, 1996), p. 736 Google Scholar. The circumstances of the destruction of Michelangelo's drawings are discussed at length in Hirst, Michael, Michelangelo and His Drawings (New Haven, 1989), pp. 17–19 Google Scholar.

6 Many scholars have made significant contributions to the study and interpretation of Michelangelo's drawings, including Henry Thode, Johannes Wilde, Paola Barocchi, Frederick Hartt, James Ackerman and Rudolf Wittkower. Perhaps Charles de Tolnay made the greatest and most comprehensive contribution; see de Tolnay, Charles, Corpus dei disegni di Michelangelo, 4 vols (Novara, 1975)Google Scholar. The best account of all of Michelangelo's architecture continues to be Ackerman, James, The Architecture of Michelangelo, 2nd edn (London, 1986)Google Scholar, published originally as two volumes (London, 1961) with an extensive catalogue (vol. II). A more recent comprehensive study is Argan, Giulio Carlo and Contardi, Bruno, Michelangelo Architect, trans. Grayson, Marion L. (New York, 1993 Google Scholar; Italian version: Milan, 1990). Contardi's historical account adds to Ackerman's with the inclusion, and discussion, of recent scholarship by others. A recent book by the German scholar Golo Mauer provides a thorough analysis and discussion of Michelangelo's practice of architecture in general, and emphasizes the role of sketching and drawing in his design process; see Maurer, Golo, Michelangelo: Die Architekturzeichnungen, Entwurfsprozes und Planungspraxis (Regensburg, 2004)Google Scholar.

7 William Wallace provides a thorough account of the administrative and construction components of Michelangelo's projects at the S. Lorenzo complex; see Wallace, William, Michelangelo at San Lorenzo, the Genius as Entrepreneur (New York, 1994)Google Scholar. Ralph Lieberman compares the contrasting spaces and architectural forms of the ricetto and the library reading room and analyses how they are experienced, noting that the design for the often neglected reading room is as sophisticated and as worthy of attention as the celebrated ricetto; see Lieberman, Ralph, ‘Michelangelo's Design for the Biblioteca Laurenziana’, in Renaissance Studies in Honor of Craig Smyth, II (Florence, 1985), pp. 571–95 Google Scholar. Frank Salmon provides a thorough analysis of the early history of the project and the three different sites at S. Lorenzo that Michelangelo and his patron Pope Clement VII initially considered; see Salmon, Frank, ‘The Site of Michelangelo's Laurentian Library’, Journal of the Society of Architectural Historians, 49 (1990), pp. 407–29 CrossRefGoogle Scholar. Silvia Catitti examines the role and influence of Michelangelo's patron, Pope Clemente VII, in the design of the ricetto, and the development of the ricetto’s stair; see Catitti, Silvia, ‘Michelangelo e la monumentalità nel ricetto: progetto esecuzione e interpretazione’, in Michelangelo architetto a San Lorenzo: quattro problemi aperti, ed. Ruschi, Pietro (Florence, 2007), pp. 91–103 Google Scholar. In the same volume, Thomas Gronneger examines and reconstructs the ill-fated stair assembled by Niccolò Tribolo with the fragments left behind by Michelangelo after his final departure for Rome in 1534, and analyses the stair built by Bartolommeo Ammannati and Giorgio Vasari in the 1550s; see Thomas Gronegger, ‘II progetto per la scala del ricetto, da Michelangelo al Tribolo a Vasari ad Ammannati: nuove interpretazioni’, in Michelangelo architetto a San Lorenzo, ed. Ruschi, pp. 105–22. Pietro Ruschi analyses and attempts a reconstruction of Michelangelo's design for the rare books room from the two sketched Casa Buonarroti plans; see Pietro Ruschi, ‘II sugello mancate: la libreria secreta’, in Michelangelo architetto a San Lorenzo, ed. Ruschi, pp. 143–55.

8 Brothers, Cammy, Michelangelo, Drawing, and the Invention of Architecture (New Haven, 2008)Google Scholar. Brothers also authored a chapter in the catalogue to the exhibition ‘Michelangelo e il disegno di architetttura’ (Vicenza, Centro Internazionale di Studi di Architettura Andrea Palladio, Palazzo Barbaran da Porto, 2006; Florence, Casa Buonarroti, 2007), introducing many of the same themes as in her book; see Brothers, Cammy, ‘Figura e architettura nei disegni di Michelangelo’, Michelangelo e il disegno di architettura, ed. Elam, Caroline (Venice, 2006), pp. 81–93 Google Scholar.

9 For example, Wittkower argues that there is no connection between the plan sketches on the Casa Buonarroti 89A recto sheet and the interior elevation study on the verso because the proportionate widths of the staircases in the plan sketch do not agree with the width of the bays in the elevation sketch. He also notes the difference between the double door in the elevation and the single door in the plan. However, one would expect to see such discrepancies as these sketches themselves were the vehicle by which Michelangelo introduced and evolved new ideas. Wittkower also interprets the plan in the top left comer of the recto side to be for a chapel located at the opposite (south) end of the reading room, without any further discussion (for further discussion see below).

10 In his consideration of Haarlem Teyler Museum A-33b-v, which includes interior elevation studies of the west wall of the ricetto and miscellaneous plans, Wittkower argues that Michelangelo was trying to unify the ricetto and reading-room elevations by placing the ricetto pilasters on a very high socle inline with the socle of the adjacent reading room. He derives the height of the ricetto socle by counting the number of steps leading up to the landing in the corner of the room, which he believes is level with the reading-room floor. Wittkower bases his interpretation on precise dimensions that he assigns to the rapidly drawn, freehand scale-less sketch through comparison with the dimensions and proportions of the final design. He then argues that Michelangelo abandoned the scheme because of the disproportionately tall socle that he himself mistakenly calculated; see Wittkower, ‘Biblioteca Laurenziana’, p. 24.

11 For a thorough discussion of the various types of drawings Michelangelo produced, see Hirst, Michelangelo and His Drawings. See also Brothers’ discussion of drawing types, the various media used by Michelangelo and other Renaissance artists, and the means by which sketching facilitated the development of ideas: Brothers, Michelangelo, pp. 9–43. Other scholars have studied Michelangelo's architectural sketches in order to understand his design process and chronology for other architectural projects. Gregory Hedberg examines a design sketch of a window that he argues Michelangelo developed initially for the Palazzo dei Conservatori and subsequently reworked for the top-floor courtyard windows of the Palazzo Farnese, and he also traces the development of the Porta Pia through an analysis of key design sketches by Michelangelo; see Hedberg, Gregory, ‘The Farnese Courtyard Windows and the Porta Pia’, Marsyas, 15 (1970–71), pp. 63–72 Google Scholar. Paul Joannides examines Michelangelo's pattern of ideas in design sketches for the Magnifici Tomb at the New Sacristy; see Joannides, Paul, ‘A Newly Unveiled Drawing by Michelangelo and the Early Iconography of the Magnifici Tomb’, Master Drawings, 29 (1991), pp. 255–62 Google Scholar. Andrew Morrogh carefully and painstakingly analyses many drawings and traces the development of Michelangelo's design for the ‘Magnifici’ tomb for the Medici Chapel at S. Lorenzo; see Morrogh, Andrew, ‘The Magnifici Tomb: A Key Project in Michelangelo's Architectural Career’, Art Bulletin, 74 (1992), pp. 578–98 CrossRefGoogle Scholar.

12 I examined the original drawings in March 1999 and June 2005 at the Casa Buonarroti in Florence, and had the opportunity to re-examine the sheets Casa Buonarroti 42A, 48A, 89A and 92A when they were on public display in the exhibition at the Casa Buonarroti, ‘Michelangelo architetto a San Lorenzo’, curated by Pietro Ruschi (May-June 2007).

13 Saalman, Howard, ‘Tommaso Spinelli, Michelozzo, Manetti and Rossellino’, Journal of the Society of Architectural Historians, 25 (1966), pp. 151–64 CrossRefGoogle Scholar (p. 154).

14 See Ackerman, Michelangelo (1986), pp. 102–03; Argan and Contardi, Michelangelo, p. 186.

15 The nineteenth-century rare books rotunda that exists today to the west of the reading room has nothing to do with Michelangelo's project.

16 For a thorough analysis and discussion of the influence of Giuliano da Sangallo's project for the S. Lorenzo façade (Uffizi 277A) and another church façade project (Uffizi 281A), probably for S. Lorenzo, on Michelangelo's early schemes for the façade, see Hemsoll, ‘Laurentian Library’, pp. 31–33.

17 Michelangelo initiated his design for the S. Lorenzo façade project (1516–19) and the Medici Chapel or New Sacristy (1519–34), with sketches that borrowed heavily from the work of others. Consideration of specific surviving design sketches for these projects helps establish a deliberate pattern of working and introduces a formal repertoire that he used in subsequent projects, including the Laurentian Library. His initial inspiration for the façade came from a scheme for the same project by Giuliano da Sangallo, while he based the chapel on Brunelleschi's Old Sacristy at S. Lorenzo. One of Michelangelo's early sketches for the façade of S. Lorenzo, found on the sheet Casa Buonarroti, A45 recto, was undoubtedly derived from a proposal for the façade by Giuliano da Sangallo, which survives on the sheet, Uffizi A280; see Ackerman, Michelangelo (1986), p. 55; and also Hemsoll, ‘Laurentian Library’, pp. 1–33. For a thorough examination of the influence of Sangallo's drawings on Michelangelo's design for the S. Lorenzo façade, see also Brothers, Michelangelo, pp. 107–21. Michelangelo transformed the various elements and motifs through the course of his development into a composition that reflected his own design intentions. In the final design, the features that survived from Sangallo's proposal and his own early sketch include the alternating wide and narrow bays, the pairs of freestanding columns on the lower level, a low attic with projecting pedestals for pairs of corresponding pilasters above, and a pediment over the centre three bays. Hemsoll also cites Bramante and Sansovino's Santa Casa in Loretto as a possible source for Michelangelo; see Hemsoll, ‘Laurentian Library’, p. 31. However, as it has more in common with Sangallo's proposals, it was probably not a direct source of influence on Michelangelo.

18 For Michelangelo's early proposals for alternate sites within the S. Lorenzo complex, see Salmon, ‘Laurentian Library’, pp. 407–29.

19 The date of this scheme is probably spring 1524. On 22 March 1524, Fattucci wrote to Michelangelo that the pope had given permission to build the library over the rooms near the Old Sacristy. On 3 April 1524, Michelangelo's third scheme was accepted in letter from Fattucci. In April/May 1524, Michelangelo carried out studies of support system for the new construction; see Ackerman, Michelangelo (1986), p. 303.

20 Ackerman believed the plan on the Casa Buonarroti 89A verso sheet is related to, and postdates, the interior elevational study on the 89A recto sheet; see Ackerman, Michelangelo (1986), p. 303. Wittkower disagreed, mainly because the plan depicts a single rather than double entrance to the reading room. However, in making his argument, he placed too much importance on dimensions and proportions; he interpreted extremely rapid and rough freehand sketches intended only for the development of ideas as if they are scaled, drafted plans; see Wittkower, ‘Biblioteca Laurenziana’, p. 28, n. 56.

21 Wittkower based his conclusion on the shape of the space, stating that it looks ‘very much like what we should call a chapel’, without further discussion or clarification; see Wittkower, ‘Biblioteca Laurenziana’, p. 44. See also Ackerman, Michelangelo (1986), p. 115.

22 One can see a similar diagrammatic reflected plan for the triangular reading room, which also appears to feature a large ocular skylight, on Casa Buonarroti sheet 79A, discussed in detail below.

23 A cove vault consists of coves or vaults rising from, and parallel to, all four walls of the space, intersecting at groins on the diagonals extending from corner to corner. In this and many other cases, the four coves sweep upwards from the walls to meet a flat, central ceiling (Fig. 24). This interpretation of the inset rectangle in the upper plan on Casa Buonarroti 89 verso as a cove vault around the perimeter of the space is reinforced by Michelangelo's subsequent interior elevation of the ricetto on the sheet Casa Buonarroti 48A recto. This drawing and Michelangelo's proposed skylight are analysed and discussed below. For the letters from Fattucci and Marzi, see also below.

24 Wittkower also noted the similarity between the stair configuration on Casa Buonarroti 89A recto and the east end of a church, but did not cite any example; see Wittkower, ‘Biblioteca Laurenziana’, p. 27. Ackerman also noted a similarity to Giuliano da Sangallo's exterior stair at Poggio a Caiano; see Ackerman, , Michelangelo, I (1961), p. 42 Google Scholar. Cattiti and Brothers also suggest that the source of inspiration for this early stair scheme was the Poggio a Caiano stair. Brothers suggests that Sangallo's stair might have been inspired by the stair at S. Miniato in Florence, and also proposes Bramante's Cortile del Belvedere as a potential source; see Cattiti, ‘Michelangelo e la monumentalita nel ricetto’, p. 95, and Brothers, Michelangelo, pp. 163 and 229.

25 The ceiling would probably have been constructed out of lath and plaster, like the ceiling, discussed below, that was probably intended for the rare books room.

26 Ackerman suggested that the rectangles in the corners of the middle lower plan are piers intended to support a vault; see Ackerman, Michelangelo (1966), p. 40, n. 6. However, considering how rapidly Michelangelo drew the sketch, it seems more likely that they are simplified corner pilasters, which, if drawn in a more careful sketch, would probably more closely resemble the folded pilasters in the corners of the Medici Chapel (Fig. 10).

27 Michelangelo derived his Medici Chapel interior elevations from Brunelleschi's Old Sacristy. However, while all four interior walls of Michelangelo's chapel consist of four pietra serena pilasters dividing the walls into three bays, Brunelleschi's interior elevations are designed in a decidedly hierarchical manner, with four pietra serena pilasters articulating only the (south) altar elevation. These pilasters divide this elevation into three bays, with the central bay opening onto a chapel, and narrow bays with doors framed by tabernacles designed by Donatello that lead to small subsidiary spaces beyond. Michelangelo's composition is more spatially unified; by continuing the ‘a-B-a’ elevation and system of pilasters around the four sides of the chapel, each element corresponds to a counterpart across the space. Above the pediments of the doors in the Old Sacristy are shallow arched niches containing terracotta relief sculptures by Donatello. Within each of the Medici Chapel's eight cramped corner bays, Michelangelo inserted unified marble door portals with sculpture niches above, which can suggest two equal storeys framed by the pietra serena Corinthian pilasters. Although in an embryonic stage of development, this is significant, as it could represent the origins of Michelangelo's idea of a tall order unifying two storeys, which he would subsequently evolve for an early scheme for the interior elevations of the ricetto, and later for the Campidoglio façades and St Peter's in Rome. The idea of a tall order also appears in embryonic form in many of Michelangelo's design sketches and drawings for the Magnifici tombs, specifically a drawing often attributed to, or copied from Michelangelo, Musée du Louvre, inv. 837r (Corpus 194r). See Morrogh, ‘The Magnifici Tomb’, pp. 578–98.

28 Wittkower, ‘Biblioteca Laurenziana’, p. 28, n. 56.

29 Michael Hirst argues that the elevation must be the west wall rather than the south wall of the ricetto because of the double doors, which do not appear on any of the plans and cannot be related to the single aisle between the desks of the reading room. However, the sketch is exploratory, so it is not surprising to see variations on ideas among the few plan and elevation studies that survive. Moreover, the width of the double doors is approximately the width of the central aisle of the reading room as built. In addition, the fact that no plans with double doors survive does not preclude the possibility that Michelangelo drew them but that they simply have not survived; see Hirst, Michelangelo and His Drawings, p. 99.

30 The similarity between the double portal in Casa Buonarroti 89A verso and the chapel at Castel S. Angelo was raised in a discussion between the author and Patricia Waddy in Rome, August 2004.

31 Through a careful reading of the ricetto’s fabric as it exists today, that is after the ‘restoration’ of 1904, Wittkower was able to deduce that Michelangelo changed the design part way through the construction process and raised the height of the ricetto considerably. He proves beyond a doubt that it was Michelangelo's initial intention for the reading room and ricetto to share a common hipped roof; see Wittkower, ‘Biblioteca Laurenziana’, pp. 11–12. See also Ackerman, Michelangelo (1986), p. 104; Cattiti, ‘Michelangelo e la monumentalita nel ricetto’, p. 95.

32 The strength of the walls of the pre-existing structure was a concern throughout the design development of the ricetto and especially of the reading room. This is clear from letters to Michelangelo from papal secretaries Fatucci and Marzi, dated 29 November and 23 December 1525 respectively. The letters are quoted and discussed below.

33 Cooper, James G., ‘The Genesis of Michelangelo's Campidoglio’ (doctoral thesis, University of Virgina, 2002), p. 314 Google Scholar. For an analysis and discussion of the project as built, the Dupérac engravings, and the author's reconstruction, see below.

34 The design development of the Campidoglio façade will be the subject of a future article by this author. Michelangelo's designs for the tombs of Popes Leo X and Clement VII at S. Lorenzo in the mid-1520s also incorporate variations on a giant order/minor order configuration. Michael Hirst mentions the similarity of the tall and minor order in the Casa Buonarroti 89A recto sheet to the giant and minor order of the Conservatori façade, but does not discuss it in detail; see Hirst, Michelangelo and His Drawings, p. 100.

35 Wittkower, ‘Biblioteca Laurenziana’, p. 28.

36 Wittkower virtually ignored this plan, suggesting that it must have been drawn long after the elevation studies; see Wittkower, ‘Biblioteca Laurenziana’, p. 28. Ackerman interpreted the sketch as I do, but does not relate it to subsequent developments. Ackerman, , Michelangelo, II (1961), p. 40 Google Scholar.

37 Wittkower, ‘Biblioteca Laurenziana’, p. 27.

38 See Wittkower, ‘Biblioteca Laurenziana’, p. 28. This interpretation is similar to that of Golo Mauer (Michelangelo: Die Architekturzeichnungen', pp. 111–17).

39 This landing is similar to Bramamte's convex / concave stair that was located on the top terrace of the Vatican Belvedere; see Hartt, Frederick, The Drawings of Michelangelo (London, 1971), p. 199 Google Scholar, n. 283.

40 Wittkower, ‘Biblioteca Laurenziana’, pp. 30–31.

41 Ackerman, , Michelangelo, II (1961), p. 40 Google Scholar.

42 Brothers, Michelangelo, p. 163.

43 Wittkower, ‘Biblioteca Laurenziana’, p. 24; Ackerman, Michelangelo (1986), p. 104.

44 As discussed above, the Casa Buonarroti sheet 89A verso includes three or four steps leading from the corner-landings to the central landing. These steps do not appear in the Teylers sketch simply because the angle of the perspective Michelangelo has rapidly drawn would mean that we would see those steps from the back. The horizontal guideline extending from the top of the step to the left, and the guideline drawn in perspective from the top step down and left, indicate the position in plan of the missing stairs and central landing. These features, and the exact number of steps, were not pertinent to the main purpose of the sketch, which was to study the west wall of the ricetto.

45 Wittkower, ‘Biblioteca Laurenziana’, p. 24.

46 Casa Buonarroti 48A recto is discussed below.

47 Ackerman also suggests that the upper elevation, with its four bays, may be a correction of the lower one; see Ackerman, Michelangelo (1966), p. 40.

48 For example, see Wilde, Johannes, Michelangelo: Six Lectures (Oxford, 1978), p. 145 Google Scholar. Brothers follows Wilde's interpretation, arguing that columns have replaced the traditional sculptural figure typically found in a niche; see Brothers, Michelangelo, p. 165.

49 Scholars have proposed other ancient buildings as sources of inspiration for the interior elevations of the ricetto, including the Tomb of Annia Regilla on the Via Appia, and the so-called House of Cola di Rienzo at the Forum Holitorium. For example, see Sinding-Larsen, Staale, ‘The Laurenziana Vestibule as a Functional Solution’, Acta ed Archaeologiam et Artium Historiam Pertinentia’, VIII (1978), pp. 213–22 Google Scholar; see also Hemsoll, ‘Laurentian Library’, p. 46. However, the lower storey of the Pantheon interior is closer to the Casa Buonarroti 48A sketch and the final design than is any other ancient source. The relationship between the columns and semi-oval recesses of the Tomb of Annia Regilla are much closer in form to Michelangelo's minor order of columns within the loggias of the Palazzo dei Conservatori, and may have served as a model for that project.

50 Cooper, ‘The Genesis of Michelangelo's Campidoglio’, p. 103. Hemsoll also identifies the lower elevations of the interior of the Pantheon as a likely source of inspiration for Michelangelo's ricetto design in Casa Buonarroti 48A recto; see Hemsoll, ‘Laurentian Library’, p. 50.

51 Quoted from Wittkower, ‘Biblioteca Laurenziana’, pp. 18–19. The original Italian reads: ‘N. S. A preso grande piacere, quando lesse, che voi vi eri risoluto a fare il ricetto, siche sollecitatelo. Ora circa alle finestre sopra tetto con quelli ochi di vetro nel palco dice N. S., che gli pare cosa bella et nuova; niente di manco non ci risolve a fare, ma disse, che e’ bisognierebe saldare dua frati delli Jesuati, che non attendessino ad altro che a nettare la polvere.’

52 Wittkower, ‘Biblioteca Laurenziana’, pp. 18–19. The original Italian reads ‘La presente è per farvi intendere come N. S. Re alli giorni passati hebbe la vostra de 7 col disegno a piedi della libreria, gli mandasti. [...] Et dice, che li ochi disegnati per dare li lumi si pensa habbino ad essere una cosa bella; ma che non sa, se la polvere, [che] riceveranno, sara maggiore che ‘ lume rendere poteranno? Et che alzando el muro duo braccia per fare le finestre, come advisate, et essendo parte del tecto posta su, et haverlo hora ad diffarlo et tramutare legami, se ‘1 reggera el peso et fara danno alla fabrica?’

53 This arc, made by a stylus, continues to the left and down, suggesting Michelangelo had begun to draw guidelines for a detail of a round element such as a column on the sheet before starting the elevation drawing.

54 Wittkower, ‘Laurentian Library’, p. 27.

55 For a complete history of the design and construction phases of the chapel, see Ackerman, Michelangelo (1986), pp. 69–94, 296–99. For Brunelleschi's Old Sacristy and other early projects, see, e.g., Klotz, Heinrich, Filippo Brunelleschi (New York, 1990), pp. 129–44 Google Scholar. Vasari tells us that it was Michelangelo's intention ‘to make it in imitation of the old sacristy’. However, while he derived both its plan and general configuration from the older chapel, he profoundly transformed what he borrowed for important functional, symbolic and compositional reasons. For the question of whether the Medici Chapel was begun by a previous architect or whether Michelangelo built the chapel from the ground up, see Wilde, Johannes, ‘Michelangelo's Designs for the Medici Tombs’, Journal of the Warburg and Courtauld Institutes, 18 (1955), pp. 54–56 CrossRefGoogle Scholar; Elam, Caroline, ‘The Site and Early Building History of Michelangelo's New Sacristy’, Mitteilungen des Kunsthistorichen Institutes in Florenz, 23 (1979), pp. 155–79 Google Scholar; Ackerman, Michelangelo (1986), p. 96; Saalman, Howard, ‘The New Sacristy of San Lorenzo Before Michelangelo’, Art Bulletin, 67 (1985), pp. 199–228 CrossRefGoogle Scholar. The pre-existing site conditions of the Medici Chapel and its neighbouring buildings are the subject of a comprehensive, well illustrated article by Pietro Ruschi; see Pietro Ruschi, ‘La Sagrista Nuova, metamorfosi di uno spazio’, Michelangelo architetto a San Lorenzo, ed. Ruschi, pp. 15–49.

56 Michelangelo's attic storey consists of lunettes over the four wide centre bays and a small order of Corinthian pilasters set in line with the large pilasters below. The interior attic storey of the Pantheon may have inspired the chapel's attic, and one could interpret the alignment of Michelangelo's attic-level pilasters above with the main storey's pilasters below as a comment on the lack of correspondence between the pilasters of the attic and main storey of the ancient temple. A more direct source for the attic may have also been Giuliano da Sangallo's octagonal sacristy at S. Spirito. As Hemsoll notes, the form of the attic storey might have been inspired by the attic of the interior of the Pantheon in Rome, just as Michelangelo based the design of the chapel's coffered dome on the ancient temple; see Hemsoll, ‘Laurentian Library’, p. 35. However, the Pantheon is nonetheless the ultimate source as it undoubtedly served as the model for the Florentine Baptistery, which in turn inspired Giuliano da Sangallo's design for the S. Spirito Sacristy. Frederick Hartt also suggested that the insertion of the attic level was in response to the problem of natural lighting; see Hartt, Frederick, History of Italian Renaissance Art (New York, 1987), p. 542 Google Scholar.

57 Judith Wolin graphically demonstrates the existence of an underlying arithmetic construct that forms the basis of the Laurentian Library design, which to her suggests neo-Platonic iconographie meaning. While her analysis proves without doubt the existence of a basic geometric construct, the notion that this represents a neo-Platonic construct, carefully ‘veiled’ by irrational architectural forms in order to invite scholarly contemplation, is difficult to accept; see Judith Wolin, ‘The Inner Eye: Speculations on Michelangelo's Architecture and Florentine Neo-Platonism’, Modulus (1980), pp. 68–72.

58 For a thorough discussion of the reception of Michelangelo's Florentine architectural forms, and its relationship to subsequent literary discussions concerning the Tuscan language, see Elam, Caroline, ‘Tuscan Dispositions: Michelangelo's Florentine Architectural Vocabulary and its Reception’, Renaissance Studies, 19/1 (2005), pp. 46–82 CrossRefGoogle Scholar. Elam notes Michelangelo's unusual columns in the ricetto appear at first glance to be Tuscan Doric, but have proportions more associated with the Corinthian order (1:10), and the abacus of their capitals with their concave sides more closely resembles a Corinthian abacus. She also points out that the capitals closely resemble those illustrated in Francesco di Giorgio's treatise on architecture; see ibid., p. 52.

59 For example, see Brunelleschi's Pazzi Chapel at S. Croce and Old Sacristy at S. Lorenzo. For a detailed analysis of Michelangelo's architectural details and a discussion of their sources, see Krieg, Stefan W., ‘Das Architekturdetail bei Michelangelo’, Römisches Jahrbuch für Kunstgeschichte, 33 (1999–2000), pp. 103–256 Google Scholar.

60 Lieberman, in his discussion of the ricetto's pietra serena and stucco, characterizes the stucco walls as ‘vital architectural plasma’; see Lieberman, ‘Biblioteca Laurenziana’, p. 573.

61 Michelangelo's deeply articulated, rhythmic façade of S. Lorenzo was not unlike the frons scenae of a Roman theatre. It is tempting to speculate that an actual ancient Roman frons scenae might have inspired Michelangelo's design, or perhaps the ancient Septizodium, a frons scenae-like structure at the base of the Palatine Hill. This comparison is also made by William Wallace; see Wallace, San Lorenzo, pp. 13 and 48. For a brief account of the Septizodium and a reproduction of a sketch by Dupérac, see Claridge, Amanda, Oxford Archaeological Guides: Rome (Oxford, 1998) pp. 144–45 Google Scholar.

62 When commissioned to rebuild the Palazzo dei Conservatori on the Campidoglio just a few years later, Michelangelo clearly based an early scheme for the main façade on the sheet Casa Buonarroti 48A recto and the two-storey final design. There is a well-known partial elevation sketch by Michelangelo on the sheet Casa Buonarroti 42A that scholars commonly identify as an early elevation study for the reading room of the Laurentian Library, and alternately as an exterior façade study for the Laurentian Library on an alternative site facing Piazza S. Lorenzo. However, more recently I have argued it to be an early façade study for the Palazzo dei Conservatori on the Campidoglio, hence its exclusion from this analysis; see Cooper, James, ‘Two Drawings by Michelangelo for an Early Design of the Palazzo dei Conservatori’, Journal of the Society of Architectural Historians, 67 (2008), pp. 178–203 CrossRefGoogle Scholar. The forms and wall articulation on this sketch are nearly identical to the Casa Buonarroti 48A recto elevation, as well as the partial plan on the sheet Parker 332 verso at the Ashmolean Museum, Oxford, identified by De Tolnay as an early partial plan of the Palazzo dei Conservatori. It is very unlikely that the partial façade study on Casa Buonarroti 42A is an interior elevation for the reading room as it clearly depicts the exterior profile of a building along its left side. Furthermore, close inspection of the original drawing reveals that Michelangelo first sketched, with black chalk, four bays and a partial fifth bay of what is clearly a three-storey palazzo-type building with a ground floor and piano nobile of approximately equal height and a low attic: proportions remarkably similar to the Quattrocento Palazzo dei Conservatori. Without completing the black chalk drawing, he then proceeded to draw variations and new ideas directly in red ink over the chalk under-drawing. The ink overlay is also exploratory and incomplete; Michelangelo did not include the attic or the fourth bay to the right. The fact that the red ink overlay does not include the attic does not allow it to be ignored, as many supporters of the Laurentian Library reading room identification conveniently do. Both the chalk and ink version depict a palazzo façade with alternating bays of equal width, with forms clearly derived from the ricetto of the Laurentian Library. The first and third bays of the ground level incorporate paired columns recessed from the outer plane of the façade. The intermediate walled bays are flanked by pilasters and feature tabernacle windows capped by segmental pediments. A plan detail, located at the centre of the sheet, confirms the relationship between the recessed paired columns and the walled bays with their flanking pilasters. The configuration of these elements is remarkably similar to the plan on Parker 332 verso. The partial plan on the sheet depicts a building that incorporates paired columns set back into a recess, flanked by pier-like walled bays with doors or windows. It would be an interesting exercise to project an elevation directly up from this plan on this sheet using the existing floor-to-floor heights of the Palazzo dei Conservatori. If one considers the frequency with which Michelangelo placed either paired pilasters over paired columns or vice versa (S. Lorenzo façade, Laurentian Library, centre stair bay and baldacchino of the Dupérac version of the Palazzo Senatorio), one would complete the piano nobile level of this drawing with paired pilasters over the paired columns below. If tabernacled windows and a low attic are added, the resulting drawing would look almost exactly like the pencil under-drawing on Casa Buonarroti 42A and the partially obscured elevation sketch that Michelangelo himself drew on Parker 332 verso (Michelangelo's ruled guidelines match the floor-to-floor heights of the palazzo as well as the bay width). Parker 332 also includes obscure circular markings to either side of the paired columns that are undoubtedly the columns of his tabernacle windows on the piano nobile, superimposed over the ground-floor plan. For supporters of the reading room identification, see Cecchi, and Natali, , Michelangelo: i disegni di Casa Buonarroti (Florence, 1985), p. 134 Google Scholar; for further discussion, see Ackerman, Michelangelo (1966), p. 102, and Wittkower, ‘Michelangelo's Biblioteca Laurenziana’, p. 22. Paul Joannides suggested the study is an exterior elevation for an early Laurentian Library scheme on an alternate site, which would have necessitated a façade on the south flank of Piazza S. Lorenzo; see Joannides, Paul, review of Wilde, Johannes, Six Lectures, Burlington Magazine, 124 (1981), p. 620 Google Scholar. Salmon and Brothers both agreed with this identification; see Salmon, ‘Laurentian Library’, pp. 407–49; and Brothers, Michelangelo, p. 163.

63 Gronegger provides a north-south section of the ricetto and the existing spaces below. He notes that the relieving arches were added to buttress vaults below the ricetto in 1533, to help support additional loads of the stair and ricetto walls; see Gronegger, ‘II progetto’, p. 121.

64 Walnut reading desks, arranged against the walls at right angles to the long axis of space, delineate the space of the central aisle. Every fourth desk corresponds to a pilaster, and the uppermost surface of the desks corresponds to the height of the socle. Tall, leaded glass windows between the pilasters on the long east and west walls of the room light the space evenly. Simple but unconventional pietra serena frames set within larger, slightly recessed panels surround the windows. The terracotta floor pattern reflects the configuration of the beams and ceiling panels that feature intricately carved motifs, consisting of ovals and in the bays above the central aisle and unusual forms resembling tabernacle window frames in the bays above the desks to either side. This unified system of beams, pilasters, desks and floor patterns creates a clear structural / spatial matrix. It is unusual in the context of medieval / Renaissance Florence where stereotomie wall mass more commonly characterizes buildings.

65 Ackerman, Michelangelo (1986), p. 117.

66 Quoted from Argan and Contardi, Michelangelo Architect, p. 197.

67 Ralph Lieberman offers many insightful observations about the experiential effects of the ricetto and reading room. See Lieberman, ‘Biblioteca Laurenziana’, pp. 571–83. The vanishing point on the horizon of a person of average height is just above the level of the desktops. Because of this acute viewing angle and the close spacing of the desks, their top surfaces appear to be connected, creating a virtual horizontal plane to either side of the central aisle, such that the transverse section of the reading room appears to be in the shape of the letter'T’.

68 Brothers describes the portals as ‘strangely thick’; see Brothers, Michelangelo, p. 175.

69 Wittkower characterizes the proposed space as the practical and physical culmination of the whole library complex: ‘The sequence of shapes — square, oblong, and triangle — would have formed a geometric progression.’ See Wittkower, ‘Bibliotecca Laurenziana’, p. 45.

70 Hartt, Renaissance Art, p. 548.

71 Wittkower, ‘Bibliotecca Laurenziana’, p. 45.

72 See Guglielmo De Angelis d'Ossat, The Complete Work of Michelangelo (New York, 1966), p. 304 Google Scholar.

73 See Ruschi, ‘II sugello mancate’, pp. 143–55.

74 ‘riducesi in tondo di sopra e tucti e’ lumi si piglion dalla volta per ché non si possono aver d'altrove’.

75 Wittkower, ‘Bibliotecca Laurenziana’, p. 45.