El Caracol, Chichen Itza, Ancient building in Mexico
El Caracol, Chichen Itza is a pre-Columbian Mayan structure at the northern end of the Yucatán Peninsula.
The dome observatory dates back to 906 AD, the earliest known date inscribed at Chichen Itza.
It played a significant role in Mayan astronomical studies.
Tours are available and it's located only 120 km from Merida.
Known as 'The Snail', its name comes from the spiral staircase inside the tower.
Source: Wikimedia