The ancient Mayan capital of Chichén Itzá casts its spell whenever you visit it but on the day of the fall Equinox, the Pyramid of Kukulcán in the Great Plaza becomes a stairway to heaven and an ancient god returns to earth.

Also known as El Castillo, the 25-meter-high pyramid is a solar clock, aligned to catch the rays of the setting sun on the spring and fall equinoxes, March 21 and September 22, respectively. Triangles of light and shadow form along the side of the north staircase and the figure of a snake appears, merging with the head of a stone serpent at the foot of the building, creating the illusion of a gigantic serpent slithering down from the heavens and across the ground towards the Sacred Cenote.

The snake symbolizes Kukulcán (also known as Quetzalcoatl in central Mexico), the feathered serpent god, returning to earth to give hope to his followers and heralding the spring planting and fall harvest seasons for the Maya.

The pyramid was built some time between A.D. 650 and 800, with later modifications during the Itzae period of glory, possibly from A.D. 1000 to 1150. The earlier temples are deep inside the pyramid we see today. When archaeologists dug through tons of stone and earth to reach the inner sanctum, they discovered a chac mool statue, the enigmatic reclining figure with hands cupped to receive the heart of a sacrificial victim, guarding the entrance and a magnificent throne in the form of a red jaguar with jade spots and eyes. The jaguar was discovered with an offering of coral, sacrificial flint knives and a turquoise mosiac disc.

The pyramid also represents the ancient Mayan calendar as the number of terraces and wall panels coincides with the number of months in the year (18) and years in a calendar round (52), respectively, and the number of steps in the staircases, including the top platform, equals 365, the days in the year.

A short distance from the Great Plaza is the round tower known as El Caracol or the Observatory. It has a viewing platform and wells, which were used by ancient astronomers to mirror starlight, and it was aligned to catch sunsets and moonsets on both equinoxes and to mark the course of Venus.

If you would like to explore one of the greatest ancient cities in the Americas and see why UNESCO declared it a World Heritage Site and a global poll in 2007 rated it as one of the Seven New Wonders of the World, book your Chichén Itzá trip now from Thomas More Travel. The snake of light and shadow is also visible the day before and after the equinox, cloud cover permitting.

Chichén Itzá is not the only Mayan ceremonial center tin the Yucatán to have temples with solar, lunar or planetary alignments. The doorway of the Temple of the Seven Dolls at Dzibilchaltún (13 miles north of Mérida) makes a perfect frame for the rising sun on the day of the Equinox.