There is a giant geoglyph in Australia that is miles tall. No one knows who created it.

60 km from the township of Marree in central South Australia lies the second largest (and most mysterious) geoglyph in the world. Known as Marree Man or Stuart’s Giant, the 4.2 km depiction of a man with a throwing stick hunting birds or wallabies remained undiscovered until June 26th, 1998, when it was sighted by charter pilot Trevor Wright as he flew over the area of Finnis Springs.

No witnesses to the creation have been found, though anonymous faxes, believed to be from the person or people responsible, were sent to media outlets. It was in one of these faxes that the name “Stuart’s Giant,” after the explorer John McDougall Stuart, was given to the figure.

Finnis Springs lies just outside the Woomera Prohibited Area, a weapons testing range used by the Royal Australian Air Force. The government of South Australia closed the site not long after its discovery following a Native Title claim by Indigenous Australians, though due to the federal government’s jurisdiction over such claims, joy flights were still being permitted over the site until at least 2010.