The Bosnian Pyramids are a series of ancient structures located in Visoko, Bosnia and Herzegovina. The site has been the subject of archaeological research since 2005, when it was first proposed that the hills of Visoko could be the remains of a pyramid complex. Since then
From Wikipedia
The Bosnian pyramid claims are pseudoarchaeological theories put forward to explain the formation of a cluster of natural hills in the area of Visoko in central Bosnia and Herzegovina. Since 2005, Semir Osmanagić, a Bosnian-American businessman based in Houston, Texas, has claimed that these hills are the largest human-made ancient pyramids on Earth. His claims have been overwhelmingly refuted by scientists but he has proceeded to promote the area as a tourist attraction.