Chichen Itza is a complex of Mayan ruins on Mexico's Yucatan Peninsula. A massive step pyramid, known as El Castillo or Temple of Kukulcan, dominates the ancient city, which thrived from around 600 A.D. to the 1200s. Graphic stone carvings survive at structures like the ball court, Temple of the Warriors and the Wall of the Skulls. Nightly sound-and-light shows illuminate the buildings' sophisticated geometry.
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It was very exciting to see one of the (new) 7 wonders of the world. Although there really isn't all too much to see, basically just stones... it's still fascinating to be at a spot where history played a big role. There are a few cool elements, such as standing in a specific spot, yelling and hearing an interesting echo.
The place is filled with tourists, but there is so much space, you never feel squeezed. It's nice to walk around and look at the different buildings, statues, and drawings, but it really doesn't take that much time to see it all. I would say a couple hours is more than enough. There are also a lot of small market stands trying to sell you anything possible, heck they'll even trade for goods that you already have (but be careful and don't get ripped off!).
It was a good experience, and I'm glad I got the chance to see this wonder, although it's not absolute must. It's more exciting to think about the correlation of this site with it's history.