Xochicalco
A trip to these ruins, which are a roughly 45-minute drive southwest of Cuernavaca, is one of the best reasons to visit the state of Morelos. Built by the Olmeca-Xicalanca people, the mighty hilltop city reached its peak between AD 700 and 900. It was abandoned a century later after being destroyed, perhaps by its own inhabitants. With its several layers of fortifications, the city appears unassailable. The most eye-catching edifice is the Pyrámide de Quetzalcóatl (Temple of the Plumed Serpent). Carvings of vicious-looking snakes—all in the style typical of the Maya to the south—wrap around the lower level, while figures in elaborate headdresses sit above. Be sure to seek out the Observatorio in a man-made cave reached through a tunnel on the northern side of the city. Through a narrow shaft in the ceiling, the Xochicalco astronomers could observe the heavens. Twice a year—May 14 and 15 and July 28 and 29—the sun passes directly over the opening, filling the room with light. From the ruins, you're also treated to an impressive view of the surrounding mountains.
Be sure to set aside at least a half-hour to explore the excellent solar-powered museum, where a wonderfully mounted exhibit of a wide variety of artifacts from Xochicalco are on display, including gorgeous sculptures of Xochicalco deities found nearby. There are dozens of other structures here, including three impressive ball courts.
