Called El Caracol (the Snail) by the Spaniards for its interior spiral staircase, this observatory, to the south of the El Osario, is one of the most fascinating and important of all Chichén Itzá’s buildings. Its circular design resembles some central highlands structures, although, surprisingly, not those of Toltec Tula.
In a fusion of architectural styles and religious imagery, there are Maya Chaac rain-god masks over four external doors facing the cardinal points. The windows in the observatory’s dome are aligned with the appearance of certain stars at specific dates. From the dome the priests may have decreed the times for rituals, celebrations, corn-planting and harvests.