El Castillo in Chichen Itza served as a temple to Kukulkan. During the spring and fall equinoxes the shadow cast by the angle of the sun and edges of the nine steps of the pyramid combined with the northern stairway and the stone serpent head carvings create the illusion of a massive serpent descending the pyramid.
Kukulkan (“Plumed Serpent“, “Feathered Serpent“) is the name of a Maya snake deity that also serves to designate historical persons. The depiction of the feathered serpent deity is present in other cultures of Mesoamerica. Kukulkan is closely related to the god Q’uq’umatz of the K’iche’ Maya and to Quetzalcoatl of the Aztecs. Little is known of the mythology of this pre-Columbian deity.
Although heavily Mexicanised, Kukulkan has his origins among the Maya of the Classic Period, when he was known as Waxaklahun Ubah Kan, the War Serpent, and he has been identified as the Postclassic version of the Vision Serpent of Classic Maya art.
The cult of Kukulkan/Quetzalcoatl was the first Mesoamerican religion to transcend the old Classic Period linguistic and ethnic divisions. This cult facilitated communication and peaceful trade among peoples of many different social and ethnic backgrounds. Although the cult was originally centred on the ancient city of Chichén Itzá in the modern Mexican state of Yucatán, it spread as far as the Guatemalan highlands.
In Yucatán, references to the deity Kukulkan are confused by references to a named individual who bore the name of the god. Because of this, the distinction between the two has become blurred. This individual appears to have been a ruler or priest at Chichen Itza, who first appeared around the 10th century. Although Kukulkan was mentioned as a historical person by Maya writers of the 16th century, the earlier 9th-century texts at Chichen Itza never identified him as human and artistic representations depicted him as a Vision Serpent entwined around the figures of nobles. At Chichen Itza, Kukulkan is also depicted presiding over sacrifice scenes.
Sizeable temples to Kukulkan are found at archaeological sites throughout the north of the Yucatán Peninsula, such as Chichen Itza, Uxmal and Mayapan. Edited from Wiki