The following figures result from measurements conducted on the various sectors of the Wall. Sector N (southern Trastevere) has been omitted for lack of statistically significant remains. Three types of measurements were made: the module of the brick facing, inside and out (with a preference for the external facings); the dimensions of the projecting faces of the towers; and the thickness of the curtains. I attempted to make measurements only where I thought the extant remains an accurate reflection of the dimensions of the structure in its original phase. In the case of modules, limited measurements were also made on the sections heightened under Honorius. The level of coverage in various parts of the circuit is not uniform, nor do I make any claims about the statistical exhaustiveness of the data, but rather present them, for whatever they are worth, in the hope that they represent a step beyond the vague and sometimes conflicting generalities traditionally advanced regarding the measurements of the Wall. With this disclaimer, they are best left to speak for themselves.

All figures are in centimeters and meters. For the modules, (int.) indicates a measurement taken on the inside of the Wall, and (Hon.) work I think executed during the campaign of 401–3. The data are arranged by category, and further subdivided by sector, identified by the letter that precedes each measurement. In exceptional cases, more specific locations are given.