El Caracol, Chichen Itza

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.

[1] The structure is dated to around AD 906, the Post Classic period of Mesoamerican chronology, by the stele on the Upper Platform.

[3] Mayan astronomers knew from naked-eye observations that Venus appeared on the western and disappeared on the eastern horizons at different times in the year, and that it took 225 days to complete one cycle.

believed to be of interest to the Mesoamerican residents of Chichén Itzá, sight lines for 20 can be found in the structure.