El Castillo seen from the south of the complex. It was the most prominent and important temple in the city. Overlooking the bay and the city's port it was dedicated to the Mayan god Kukulkan and is located on the site's highest point. In addition to its religious function as a temple, El Castillo also played a critical role operating as a lighthouse, parts of the structure were lanterns lit every night to aid sailors reach town during the dark wee hours of the night.