These enormous mummies are topped with actual human skulls and set menacingly into a Peruvian cliffside.

Before researchers were able to hike up and explore the strange mummies, they watched over the Utcabamba Valley from a cliffside in a river canyon in Peru known as the Sarcophagi of Caraja (or Karijia).

The seven standing burial capsules (originally eight, but one of them collapsed following a 1928 earthquake) were built somewhere in the 15th century by the Chachapoya culture, and they are situated over 700 feet above the valley floor. The sarcophagi survived remarkably intact because of their seemingly improbable location, although most of the Chachapoya civilisation was lost after being subjugated by the Incan people and simply through time. Each of the extraordinary eight-foot-tall statues is made of clay and gold and is embedded directly into the rock face. Even the human skulls that were placed atop the sarcophagi are still there in some of the burials.

Researchers weren’t able to scale the cliff wall and examine the mummies until the middle of the 19th century, at which point they were able to date them and make educated guesses about how they were made. The original designers of these burials are thought to have drawn inspiration from natural outcroppings that were eventually demolished either intentionally or naturally. The surrounding rock walls shield the sarcophagi from the weather, but birds and other tiny animals have caused some damage. To protect the ancient organs from further predation, the researchers removed the contents of the sarcophagi.