I visited Chitzen Itza in the early 1980s. While there I went up into the center of this pyramid. The passage was extremely steep and narrow and ended in a room where there was a panther(?) of onyx. Quite impressive but not for those with claustrophobia!
The second photo is of the area where sacrifices were made. After going up and down this one, I couldn't walk the next day! Then I learned that you ascend and descend from side to side, not straight up and down. Live and learn!