When the Pyramid of the Sun and the Pyramid of the Moon were completed, the locus of construction at Teotihuacan shifted to the southern end of the Street of the Dead, where a complex called the Ciudadelaa sunken plaza large enough to hold most of the city's inhabitantswas centered on the Temple of the Feathered Serpent. Completed in the early third century A.D., the pyramid is flanked by two apartment compounds where the city's rulers may have lived. The initial construction phase of the Temple of the Feathered Serpent appears to have been marked by a mass burial. Grave pits containing some 200 individuals in and around the pyramid's core were discovered in the late 1980s. Presumed to be warriors, the militaristic connotations have influenced interpretations of the building's exterior. The Temple of the Feathered Serpent may have been the first use of the architectural profile known as talud-tablero at Teotihuacan. In talud-tablero, a rectangular panel (the tablero) sits atop a sloping panel (the talud). Both surfaces could be decorated, most often with mural painting. This distinctive profile dominates the architecture of the entire site, and is taken as a marker of Teotihuacan influence when it appears in other locations throughout Mesoamerica. The balustrade and tableros of the Temple of the Feathered Serpent feature large tenoned serpent heads with low-relief bodies upon which elaborate mosaic headdresses appear at intervals. The headdresses, with their prominent eyes and fangs, were integral to military iconography at Teotihuacan and were similarly used throughout Mesoamerica.