During the conference we had a day off, I went on an organised tour to Chichén Itzá, the oldest Mayan city. This was fantastic, most of these buildings are 1000 years old. This day it reached 40 degrees C, and 95% humidity. I saw two ambulances speeding around.
This pyramid (Temple of Kukulcan (the Maya name for Quetzalcoatl), often referred to as "El Castillo" (the castle) is unbelievably steep, at about a 45 degree angle. Thats why there is a rope to help people walk up the steps. I found out the next day that 20 people are killed each year falling off it!. The view from the top was worth the climb though.