perhaps even women, the game also had important ritual aspects, and major formal ballgames were held as ritual events, often featuring human sacrifice. Astronomy Mesoamerican astronomy included a broad understanding of the cycles of planets and other celestial bodies. Special importance was given to the sun, moon, and Venus as the morning and evening star. Observatories were built at some sites, including the round observatory at Ceibal and the "Observatorio" at Xochicalco. Often, the architectural organization of Mesoamerican sites was based on precise calculations derived from astronomical observations. Well-known examples of these include the El Castillo pyramid at Chichen Itza and the Observatorio at Xochicalco. A unique and common architectural complex found among many Mesoamerican sites are E-Groups, which are aligned so as to serve as astronomical observatories. The name of this complex is based on Uaxactun's "Group E", the first known observatory in the Maya area. Perhaps the earliest observatory documented in Mesoamerica is that of the Monte Alto culture. This complex consisted of three plain stelae and a temple oriented with respect to the Pleiades. Symbolism of space and time It has been argued that among Mesoamerican societies the concepts of space and time are associated with the four cardinal compass points and linked together by the calendar. Dates or events were always tied to a compass direction, and the calendar specified the symbolic geographical characteristic peculiar to that period. Resulting from the significance held by the cardinal directions, many Mesoamerican architectural features, if not entire settlements, were planned and oriented with respect to directionality. In Maya cosmology, each cardinal point was assigned a specific color and a specific jaguar deity (Bacab). They are as follows: Hobnil, Bacab of the East, associated with the color red and the Kan years Can Tzicnal, Bacab of the North, assigned the color white and the Muluc years Zac Cimi, Bacab of the West, associated with the color black and the Ix years Hozanek, Bacab of the South, associated with the color yellow and the Cauac years. Later cultures such as the Kaqchikel and K'iche' maintain the association of cardinal directions with each color, but used different names. Among the Aztec, the name of each day was associated with a cardinal point (thus conferring symbolic significance), and each cardinal direction was associated with a group of symbols. Below are the symbols and concepts associated with each direction: East: croco dile, the serpent,