El Caracol, the Observatory, is a unique structure at pre-Columbian Maya civilization site of Chichen Itza. El Caracol, which means 'snail' in Spanish, is so named due to the spiral staircase inside the tower. The structure is dated to around AD 906, the Post Classic period of Mesoamerican chronology, by the stele on the Upper Platform. It is suggested that the El Caracol was an ancient Mayan observatory building and provided a way for the Mayan people to observe changes in the sky due to the flattened landscape of the Yucatán with no natural markers for this function around Chichen Itza. The observers could view the sky above the vegetation on the Yucatán Peninsula without any obstruction.