The Pyramid Claim
In 2005, Bosnian-American businessman Semir Osmanagić proposed that a cluster of hills near the town of Visoko were not natural formations, but a massive, ancient pyramid complex. The central feature is Visočica hill, which he renamed the "Bosnian Pyramid of the Sun." At over 220 meters, he claims it is taller than the Great Pyramid of Giza (147 meters). Other hills in the area were given names like the Pyramid of the Moon, Dragon, and Love.
Osmanagić's "Archaeological Park: Bosnian Pyramid of the Sun Foundation" asserts these are the oldest pyramids on Earth. Radiocarbon dating of organic material found above alleged concrete blocks has produced dates of over 12,000 years, with some claims extending as far back as 34,000 years. The foundation's research shows analyses of rectangular blocks covering the "Pyramid of the Sun," identifying them as superior form of ancient concrete. This material, they state, is harder and has lower water absorption than modern equivalents. Excavations have also focused on a nearby network of passages called the Ravne Tunnels, called a prehistoric underground labyrinth connecting the pyramids. This network is claimed to be 3.8 kilometers long.
The Geologic Explanation
Mainstream geologists and archaeologists overwhelmingly reject these claims. The scientific consensus is that the hills are natural formations known as flatirons. These are common geological features, not unique to Bosnia, formed by the erosion of dipping layers of sedimentary rock. A 2006 analysis by geologists from the University of Tuzla concluded that Visočica hill is composed of Miocene-era clastic sediments (dating from 5 to 23 million years ago) and that its shape is the result of natural tectonic and erosional processes.
The so-called concrete blocks are identified by geologists as a natural conglomerate rock called breccia—a stone composed of broken, angular fragments of other minerals cemented together. The European Association of Archaeologists has issued a formal declaration calling the project a "cruel hoax," expressing concern over the damage being done to legitimate medieval and Roman archaeological sites on and around the hills. Critics suggest the Ravne Tunnels are likely remnants of medieval mining operations, not a prehistoric network. Despite the scientific opposition, the site is a significant tourist destination, reshaping the local economy of Visoko.