The answer is "it is in the shape of serpent".
Overwhelming the focal point of Chichén is the Temple of Kukulkan (the Maya name for Quetzalcoatl), frequently alluded to as "El Castillo" (the castle). This progression pyramid has a ground design of square patios with stairways up every one of the four sides to the sanctuary to finish everything. On the Spring and Autumn equinox, at the rising and setting of the sun, the edge of the structure throws a shadow in the state of a plumed serpent - Kukulcan, or Quetzalcoatl - along the west side of the north staircase. On these two yearly events, the shadows from the corner levels crawl down the northern side of the pyramid with the sun's development to the serpent's head at the base.