Bosnian Pyramid of the Sun

43.9786°N, 18.1779°E.

The Bosnian Pyramid of the Sun at Visoko, Bosnia and Herzegovina — a triangular hill 213 metres tall claimed by the Sarajevo-based researcher Semir Osmanagić since 2005 to be a 12,000-year-old artificial pyramid built by an unknown pre-Holocene civilisation. Mainstream geological and archaeological investigation — including expert assessment by the European Association of Archaeologists in 2006 and 2007 — has determined the hill to be a natural geological formation called a flatiron, produced by tectonic uplift and differential erosion of the local sandstone-mudstone-clay sequence. The associated tunnels excavated by Osmanagić's team are documented as a combination of natural karstic features and modern excavation. Despite the mainstream consensus, the site has become a major tourism destination drawing approximately 100,000 visitors per year and has been visited by senior Bosnian political figures including the country's presidents.

A natural geological formation interpreted as an ancient pyramid by a nationally significant alternative-archaeology movement, with the dispute between mainstream geology and the local interpretation continuing unresolved in Bosnian public discourse since 2005.