Teotihuacán was probably laid out from its inception according to a master plan intended to express a specific worldview in material form. It is argued that a proposed measurement unit of 83 cm reveals mesoamerican calendrical numbers such as 52 (x 10), 73, 260, 584, and 819, when applied to city axes and major monuments. The channelized Río San Juan divides the central zone into two sections: the watery underworld to the south, especially represented at the Ciudadela, and to the north the earthly representation of the passage from the underworld to the heavens, where the Sun Pyramid at the center symbolizes a sacred time bundle in the 260-day ritual calendar. The sacrificial burial complex found at the Feathered Serpent Pyramid seems to have been a part of the city-foundation program, and the iconography of the pyramid apparently commemorated this dramatization of the creation of time and space.