El Castillo was built on top of an earlier structure. The picture below shoes sections of the older pyramid including platforms and steps.
It's hard to look at the pictures and get a sense of how big an area the ruins cover, the site is 2.5 sq. miles.
This is the ball court, again a much bigger court than we saw at any other ruins. High on the wall on the left side of the court you can see a ring which the ball had to get through. The players could use elbows, knees and hips to hit the ball.
Two big iguanas sunning themselves. We saw these guys everywhere.
El Caracol, the observatory
El Mercado (the market)
Edificio de las monjas (Edifice of the nuns) and La Iglesia (the church)
The Edifice of the Nuns was built over an older structure. An archaelogist in the 20th century susupected this and used dynamite to blow away part of the exterior, revealing the older structures inside. You can still see his results.
The price of your ticket includes a nightly sound and light show so we went back to the ruins to check it out. The story of the site and the Mayan peoples was narrated as different temples were lit with various colors and effects. It was pretty cool, here's a picture to give you an idea (it was cooler in person).