El Castillo, Chichen Itza

This building is known as El Castillo, "The Castle" or as the Piramide de Kukulkan, the Pyramid of Kukulkan, the Plumed Serpent. Twice a year, on the equinoxes, the light of the sun makes a play of light and shadow which makes it look like a serpent is slithering along the steps of the pyramid.