Contemplating the 30-meter-high ancient pyramid at Mayan archeological site Chichén Itzá in the blazing Yucatán sunlight, I was awestruck by the structure’s complexity. Not just because of the pure historical ramifications of the pyramid and temple , but also because of its timekeeping capabilities. Chichén Itzá’s most famous structure was actually built to be the world’s largest calendar And this at a time when calendars didn’t even exist!