Tulum is a Mexican town near which - on a steep cliff on the coast of the Caribbean Sea - there are ruins of the Maya town. The most famous architectural element of this town is the so called El Castillo, a tower considered to be an old lighthouse (the Maya settlement used to function as a sea port). However, some archeologists claim that the tower was not a lighthouse, but a guarding tower, from which guards were meant to look out for invaders.
