The Incan Temple of the Sun in Cusco has long been a visual and cultural jewel of the ancient empire. But there’s even more to admire below ground. Recently, archaeologists confirmed a long-held rumor: the existence of a labyrinth of underground tunnels extending out from the temple, sometimes over a mile in length.

First hinted at in historical texts that date as far back as the 16th century, researchers have wondered if this labyrinth—known as a chincana—was real. Turns out, it is.