Chichen Itza is one of the most spectacular archaeological sites of the Mayan Culture located at a relatively short distance from Cancun and Riviera Maya. Today we can admire what was their impressive religious and political civic complex. For the spring and autumn equinoxes, people observe an optic illusion that is possible by combining the geometric construction and the setting of the sun. This way when the sun goes descending slowly, it forms triangles of light and shade, the figure of a snake that lowers smoothly from the north stairway, and when the sun is in an exact point, with clarity we can look at the complete figure of the snake connecting with the head, (a splendid sculpture that lies at the base of the temple). This mystical moment is known as the descent of Kukulcán and is linked to the beginning of the agricultural cycle.