At 25m (82ft), this structure was built over an original pre-Toltec building from around AD 800, with the current pyramid dedicated to Kukulcan, a Mayan snake god. The whole pyramid represents a calendar as there are four staircases with 91 steps each plus the temple platform, making 365 steps in total.

El Castillo (the Castle) is Tulum’s main pyramid, and was used as an ancient lighthouse. Two small windows at the top allowed sailors to navigate the bay at dusk. If merchant boat captains could see daylight through both windows as they sailed in, they wouldn’t crash into the reef hiding just below the water.