Nestled in the heart of the vast Andean ranges of Cauca, Colombia, the Tierradentro ruins were once hidden from the outside world by decades of civil war.

Little is known about Tierradentro, meaning “inside earth,” but the UNESCO World Heritage Site is unlike anywhere else in the world. The ruins are made up of a cluster of 162 ancient burial chambers—called hypogea—that are believed to date back to between 600 and 900, before Spanish colonization. 

Entrances to the tombs speckle four towering peaks, and sets of stairs carved into the volcanic rock descend into underground chambers, some no larger than a coat closet and others with multiple rooms. The walls are painted with vivid red, black, gray, and white geometric patterns and giant monolithic faces are etched into pillars on the sides and centers of the rooms. The tombs are believed to have been created for the ancient society’s elite: homes for the dead. 

Despite concerns that the ruins are deteriorating, the detailed paintings have stood the test of time. Between Tierradentro and the more than 500 megalithic statues in neighboring San Agustín, the zone is the continent’s largest collection of prehistoric sculpture—and that includes Chile’s Easter Island.