Chichén Itzá main temple top

The United Mexican States (Spanish:  Estados Unidos Mexicanos (help·info)), commonly known as Mexico (pronounced ⁱ/ˈmɛksɨkoʊ/; Spanish: México, IPA: [ˈmexiko] ( listen)), is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of Mexico. Covering almost two million square kilometres (over 760,000 sq mi), Mexico is the fifth largest country in the Americas by total area and the thirteenth largest independent nation in the world. With an estimated population of over 112 million, it is the eleventh most populous country and the most populous Spanish-speaking country. Mexico is a federation comprising thirty-one states and a Federal District, the capital city.

Chichen Itza, Spanish: Chichén Itzá ( /tʃiːˈtʃɛn iːˈtsɑː/; from Yucatec Maya: Chi'ch'èen Ìitsha', /IPA:tɕʰɨɪʼtɕʼeːn˧˩ iː˧˩tsʰaʲ/ "at the mouth of the well of the Itza"), was a large pre-Columbian city built by the Maya civilization. The archaeological site is located in the municipality of Tinúm, in the Mexican state of Yucatán.

El Castillo (Spanish for "castle"), also known as the Temple of Kukulkan, is a Mesoamerican step-pyramid that dominates the center of the Chichen Itza archaeological site in the Mexican state of Yucatán. The building is more formally designated by archaeologists as Chichen Itza Structure 5B18.

Built by the pre-Columbian Maya civilization sometime between the 9th and 12th centuries AD, El Castillo served as a temple to the god Kukulkan, the Yucatec Maya Feathered Serpent deity closely related to the god Quetzalcoatl known to the Aztecs and other central Mexican cultures of the Postclassic period.

The pyramid consists of a series of square terraces with stairways up each of the four sides to the temple on top. Sculptures of plumed serpents run down the sides of the northern balustrade. During the spring and autumn equinoxes, the late afternoon sun strikes off the northwest corner of the pyramid and casts a series of triangular shadows against the northwest balustrade, which some believe creates the illusion of a feathered serpent "crawling" down the pyramid. Each of the pyramid's four sides has 91 steps which, when added together and including the temple platform on top as the final 'step', produces a total of 365 steps (which is equal to the number of days of the Haab' year).