You may not realize it, but this is a particularly odd structure in the Mayan world:

It’s a pyramid called Xaibe at the ancient ruins of Cobá in Mexico’s Yucatán peninsula. The name comes from a Maya term for a crossroads, since it’s at the junction of four Maya roads — and it’s nearly unique in being a Maya pyramid with an elliptical (vs. rectangular) footprint. It *may* have been used as a lookout tower, but I’ve never seen anything resembling an authoritative statement on that.