Chichen Itza's pyramidal temple El Castillo.  Ninety-one steps
on four staircases equals 364.  A final step platform at the top
equals 365, the days of the solar year.

Chichen Itza Equinox Event

• Equinox

In a mysterious phenomenon that occurs twice each year, Chichen Itza displays the Maya culture's engineering genius and their fascination with the solar cycles, the equinox event. (link)

     When the hours of daylight equal the hours of darkness, during the equinox of March 21 and September 21, thousands of people gather at Chichen Itza to watch as a shadow forms on the side of the northeast stairway of the pyramidal temple, El Castillo.

A Mayan skull shows intentional deformation

The shadow takes the undulating shape of a serpent as it appears to move down the balustrade of the stairway.  The shape, a combination of light and shadow, continues to descend as the sun goes lower in the sky and then the shadow terminates at the sculptured  head at the bottom of the stairs, the Feathered Serpent, Quetzalcoatl, the god of the Mayas and the Toltecs. (link)

The Pyramid El Castillo or Kukulcan is
 built  in the Toltec style.  The 91 steps
coincide with the number of days between
The zenith day at the Equator and the
 zenith day at the Tropic of Cancer

• El Castillo

El Castillo, the pyramidal temple also called Kukulcan, is the highest temple at Chichen Itza (link)  and the highest built by the Maya in Mexico. Its four stairways each contain 91 steps for a total of 364 steps. One final step to the platform top equals 365 steps, the number of days in the solar year.

The pyramid itself rises on nine stepped platforms that rise at a 54 degree angle. These stepped platforms with their rounded corners are what cast the afternoon shadow on the northeast facing stairway. The stairways rise at a 45 degree angle.

On the afternoons of the equinox, when the sun is directly over the equator, these building details coincide in an amazing display to create a shadow and light image that appears to move down the side of the staircase.  The event culminates as the body of the serpent connects to the sculptured head at the bottom of the stairway.    Video (link) 

Transportation to Chichen Itza (link)

Chichen Itza Lodging  (link)