features aligning to celestial events. Round temples, often dedicated to Kukulcan, are perhaps those most often described as "observatories" by modern ruin tour-guides. It is now known, however, that many buildings of different types and uses were oriented on astronomical grounds, mostly to sunrises and sunsets on specific dates. The dates recorded are concentrated in four agriculturally significant seasons and tend to be separated by multiples of elementary periods of the calendrical system (13 and 20 days), suggesting that the orientations allowed the use of observational calendars intended to facilitate a proper scheduling of agricultural and associated ceremonial activities. Although most of the important Maya buildings were oriented on the basis of astronomical criteria, their primary functions were religious, residential or administrative; the label "observatory" applied to any structural type is thus hardly warranted. Ballcourts As an integral aspect of the Mesoamerican lifestyle, the courts for their ritual ballgame were constructed throughout the Maya realm, often on a grand scale. The playing alleys of ballcourts were defined by two long walls. Courts built earlier in Maya history (as at Cobá) had sloped sides, while ones built later (as at Chichén Itzá) had vertical sides. Frequently, the ends were enclosed so as to create an -shaped court when viewed from above. When the Maya played games in the Ballcourts, the ball was made of solid rubber and was sometimes as much as a foot in diameter. It was passed between teams ranged on opposite ends of the court. The players could hit it only with their knees or hips, much like football or soccer today. Points could be scored when the opponents failed to return the ball correctly. In central Mexico, and in late times in Yucatán, rings of stone were set high up in the side walls of the court. It was considered a particular triumph for a player to knock the ball through the ring. Cave sites There are also cave sites that are important to the Maya. Maya cave sites include Jolja Cave, the cave site at Naj Tunich, the Candelaria Caves, and the Cave of the Witch. There are also cave creation myths among the Maya. Some cave sites are still used by the modern Maya in the Chiapas highlands in Mexico. Some of these caves were completely or partially artificial. See also Ancient American engineering Mayan Revival architecture (twentieth century) Triadic pyramid Twin pyramid complex References