The ruins of the 11th-century walled city are a popular attraction for visitors staying in Cancun and Riviera Maya, so come early to beat the crowds. You can get a guided tour while you’re there, which is well worth it for context and better understanding of the Mayan culture. Many visitors like to end the tour by spending the rest of the afternoon on the gorgeous public beach by the ruins. Facilities are sparse, but there is a small changing room. The 15 pyramids are illuminated in shades of red, blue, and amber for 45-minute nighttime tours. The "Visitas Nocturnas" experience includes an audiovisual introduction to the Mayan site, followed by a guided walk through part of the largest structure, El Castillo, whose labyrinthine passages lead 150 feet down to the Caribbean.