Maya city in the Yucatán, founded 432 A.D. One of the largest and most impressive ancient cities of the Maya in the Yucatán, Chichén Itzá is thought to have been founded in 432 A.D., but reached its apogee between 964 and 1214 A.D. The site is notable for many imposing structures including the pyramid of Kukulkán (El Castillo), and the only round Maya building yet discovered, the Caracol observatory.