Chichen Itza is probably the most famous pyramid in Mexico. Actually, Chichen Itza is the name of the entire archaeological zone. The pyramid itself is called "El Castillo," and was the site of the gruesome religious ceremonies. The Mayans were an amazing people, not the least because of their knowledge of astronomy. On the day of the Spring Solstice (March 21), the afternoon sun hits the main staircase of El Castillo in such a way that it looks like a serpent wriggling down to the bottom. And of course, at the end of the serpent is the head of the plumed serpent Kulkulkan.
Inside the pyramid, up a dimly lit and narrow staircase, you'll find the ceremonial reclining figure Chac Mool (on whose lap the beating hearts of human sacrifices were placed), as well as a beautiful Jaguar Throne.
In the central grouping of buildings you'll find the circular observatory, also called the Caracol, as well as the Nunnery and assorted other buildings. Note that the Spaniards named most of these structures—the Maya certainly did not call that large apartment-like structure "The Nunnery." In fact, I'd guess that if the Mayans and Toltecs had been around long enough to meet the Spanish (the Mayan/Toltec civilization disappeared hundreds of years earlier), they'd have given new meaning to the concept of "having a Nun over for dinner."
Chichen Itza is a large and imposing archaeological zone, and easily deserves 2 days of exploration. If that is your intention, there is another of the wonderful Club Med Archaeological Villas on-site. Tidy rooms, great food, wonderful pool, FANTASTIC location, and discount prices.
Our favorite area is the Ball Field. We have yet to figure out exactly what game was played there, but with circular "goals" mounted in the walls, they probably used some kind of ball in a game that resembles soccer. There is a game still played in the area in which the players hit the ball with their hips instead of their feed. And, of course, if your team lost the game, you got to visit our old friend Chac Mool.
One structure, the name of which escapes me, seems to be constructed entirely of human SKULLS! Now as violent as the Mayans were, I understand it was the Toltecs who were the real "head hunters."
If you are still looking for adventure after your 2 days at Chichen Itza, I recommend you drive to Vallodolid and go about 4 miles southeast to the Cenote Dzinup (also spelled Dzitnup). It's deep underground, with only a small hole in the ceiling for light. When we were there, a crowd of Germans were on-site, and my sister-in-law (devil that she is), swam out to the far side of the Cenote and screamed "Snakes!"
We had the place to ourselves after that . . .