This guy has been only partially excavated, so you can see the mound that it was and the structure revealed beneath it.
Guide book notes: the Maya were the first to use the number 0 in a system of mathematics; they calculated the lunar cycle that is different to today’s by 7 minutes; they had no metal tools (but obsidian, a really sharp rock…); no beasts of burden (but plenty of slaves…); and they never used a wheel for anything but children’s toys.