Equinox at Chichen Itza, Mayan Calendar Magic in the Yucatan
It wasn’t planned, but when I arrived in Cancun I learned we were just weeks away from the spring equinox, a time when the ancient Mayan calendar (which is what the so-called pyramids are) would do a shadow effect of a snake crawling down the structure. (And traveling without a schedule enables you to hang around for things you discover along the way or for surprises.)