The recent discovery of a cenote deep beneath the Pyramid of Kukulcan in the Great Plaza at Chichen Itza is a reminder that this ancient Mayan capital still holds many secrets. If you haven’t visited this majestic UNESCO World Heritage Site before or you did so many years ago, then perhaps it is time to book a trip and learn about some of the discoveries archaeologists have made in recent years.

If you are here in September, why not join thousands of other visitors and local people who gather to celebrate the Equinox on September 22 and 23? You’ll see the famous Pyramid of Kukulcan transformed by the shadow of a serpent seemingly slithering down from the heavens.

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 days of the spring and fall equinoxes in March and September. Triangles of light and shadow form along the side of the north staircase and the body of a snake appears. It merges with the head of a stone serpent at the foot of the building, creating the illusion of a gigantic reptile coming down from the sky and rippling across the ground towards the Sacred Cenote.

The snake symbolizes Kukulcan (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 of Kukulcan 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 mosaic 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 Chichen Itza trip now. The snake of light and shadow is also visible the day before and after the equinox, cloud cover permitting.

If you would like to stay longer, why not sign up for the Thomas More trip that takes in the Hubiku cenote, Valladolid, an afternoon tour of Chichen Itza and the brand new evening Light and Sound Show, a marvel of computer-generated art and video mapping? tourdesk@royalresorts.com www.thomasmoretravel.com

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