In the 1200's, Tulum was an important Mayan seaport along the Yucatan coast. It was the only Mayan city built on a coast. It remained inhabited well after the arrival of the Spanish. The Temple of the Wind God (Templo del Dios del Viento) served as a lookout post and also a storm warning system. It is said the building was constructed with a hole in the roof which produces a whistle when high winds blow. When the Mayans heard it, they knew a hurricane was approaching and to leave the city and seek shelter in land. There is a small altar inside.