From the market, bear left (away from the Castillo, just visible through the trees) until you meet the path leading to the site’s southern entrance.

You’ll pass the Osario (Ossuary) also known as the Tomb of the High Priest. Like a miniature version of Castillo, the pyramid at one time had four stairways on each side and a temple at the crest.

From the top platform, a vertical passageway leads into a cave where seven tombs were discovered, along with numerous copper and jade artifacts indicating the deceased were of special importance (and hence the temple’s name). Continuing on, you’ll pass two more large structures, Casa del Venado (House of the Deer) and Casa Colorada (Red House).

But the highlight of this portion of Chichén Itza is El Caracol (The Shell), also known as the Observatory and perhaps the most graceful structure at Chichén Itzá.

A two-tiered circular structure is set atop a broad rectangular platform, with window slits facing south and west, and another aligned according to the path of the moon during the spring equinoxes. Ancient astronomers used structures like this one to track celestial events and patterns—the orbits of the Moon and Venus, and the coming of solar and lunar eclipses, for example—with uncanny accuracy.

Beyond the Caracol is the Nunnery, so-named by Spanish explorers who thought it looked like convents back home. Judging from its size, location, and many rooms, the Nunnery was probably an administrative palace. Its exuberant facades show strong Chenes influence, another example of the blending of styles in Chichén Itzá.