I visited there a good few years ago (I think about 10), when you could still climb the stairs to the top. They were so steep and I remember coming down very, VERY carefully - because there's nothing to stop you falling all the way if you tripped. I actually came down shuffling on my ass at one point.
What an amazing place though! We were told about a concert that Pavarotti did at Chitchen Itza, where you could hear his voice echo off the buildings (the acoustics there are so good). What an amazing concert that would've been!