The 1,500-year-old pyramids, located just 75 miles from the town of Merida, may be less popular than their counterparts in Egypt, but they're just as striking. The main attraction at this Mayan site is El Castillo, the 78-foot, 91-step central pyramid. For those visiting this part of the world during the summer months, it's wise to arrive in the early morning or late afternoon when temperatures are cooler. But the absolute best time to travel to "the mouth of the well of Itza" is at sunset during the spring or autumn equinoxes when shadows give the illusion that a large serpent is slithering down the pyramid. Other site structures include the Temple of the Warriors, the Ball Court and Tzompantli, the Wall of Skulls.