This is the twenty-fifth Special Section published in Ancient Mesoamerica, and therefore it represents something of a milestone in the history of the journal. The goal has been to present in each special section a collection of related papers from a single project or region or on a selected topic to provide readers a tightly integrated summary of current research and interpretations. Certainly one of the most compelling and provocative special sections we have published was “Urban Archaeology at Teotihuacan” which appeared in vol. 2, no. 1 (1991). This collection of papers featured two stunning articles on the Feathered Serpent Pyramid, then often referred to as the Temple of Quetzalcoatl. Constructed in the early third century A.D., the Feathered Serpent Pyramid, along with the Sun Pyramid and the Moon Pyramid, was one of the three most powerful monuments in the sacred urban landscape of Teotihuacan. Rubén Cabrera Castro, Saburo Sugiyama, and George L. Cowgill (1991) reported on excavations in the 1980s of the Feathered Serpent Pyramid and the investigation of more than 137 sacrificial burials, including more than 70 males identified as soldiers because of associated offerings, discovered at the base of and underneath the pyramid. In the second article, Alfredo López Austin, Leonardo López Luján, and Saburo Sugiyama (1991) presented their brilliant iconographic analysis of the sculptural facades of the Feathered Serpent Pyramid, arguing that the monumental structure was dedicated to the myth of the origin of time and calendric succession, a tangible cosmogonic proclamation that Teotihuacan was “the place where time began.”