Fuerte de San Felipe Bacalar
This 17th-century stone fort was built by the Spaniards using stones from the nearby Maya pyramids. It was originally constructed as a haven against pirates and marauding bandits, then was transformed into a Maya stronghold during the Caste Wars. Today, the monolithic structure, which overlooks the enormous Laguna de Bacalar, houses government offices and a museum with exhibits on local history (ask for someone to bring a key if museum doors are locked).