Semir Osmanagić has become something of a national hero in Bosnia for his claims that a collection of hills in Visoko, 24 km northwest of Sarajevo, are in fact giant ancient pyramids. He has successfully commercialized this theory through tourism to a network of allegedly prehistoric tunnels that connects these “pyramids” underground.

Inside the 3.8-kilometer-long Ravne Tunnel complex, which is operated by Osmanagić’s Bosnian Pyramid of the Sun Foundation, there are supposed ceramic plates said to have healing powers. There are also alleged runestones in the tunnels, and water from them is sold with promises of healing powers. In addition to offering tours of the tunnels, the Foundation sells opportunities to participate in their further excavation.

Although Osmanagić has been well-received by many Bosnian nationalists, he has been ridiculed by the scientific community. A study found no evidence to suggest that the “pyramids” are anything other than natural hills. As for the tunnels themselves, they are likely remnants of medieval mines or tunnels dug by Yugoslav Partisans during World War II. A geologist found that the runes are likely modern additions. Osmanagić himself has admitted to widening the tunnels for tourist usage.