Closer on the right; The House of Chultun (Maya word meaning: "dug out collector for rainwater") which housed a cistern for collecting water. In the middle of the City Square. 2-Just behind it, in a more yellowish color is the Temple of Frescoes, a three level structure symbolizing the Mayan understanding of the universe (Uunderworld; the realm of the dead, The Ground world, the place for us, the living, and the Heaves, the realm of the Gods. This building was a was used as a solar observatory. 3-Big, tall castle-like building at the end is "El Castillo". El Castillo 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.