El Caracol is one of Chichen Itza's most distinctive buildings, a round tower set on a large platform in a city otherwise dominated by stepped pyramids, courts, and rectangular temples. Its Spanish name means "the snail", a reference to the spiral stair inside the structure.
The building is usually interpreted as an astronomical observatory, with alignments connected to sky watching and especially to Venus. Even if you are moving quickly through the site, it is worth leaving the main pyramid area for El Caracol because it shows a different side of Maya architecture and scientific attention.