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.

Direct study of the site by geologists, archaeologists, and other scientists has demonstrated that the hills are natural formations known as flatirons, and that there is no evidence that they were shaped by human construction. The European ᴀssociation of Archaeologists has condemned the so-called “Bosnian pyramids” as a “cruel hoax”; along with various other scholars they are also concerned about damage being done to genuine archaeological and paleontological sites: a medieval Bosnian castle, Roman fortifications, and other ancient remains. Osmanagić initiated excavations in 2006 and has since reshaped one of the hills, making it look like a stepped pyramid The academic community has called for the government to end funding of excavations and disruption of the site because of the damage to true archaeological resources.

Many scholars have noted that the claims have been used for serious ideological, political and economic gains by various factions in Bosnia. Although Osmanagić’s claims have been completely disproved by the scientific community, the Visoko area in recent years has attracted pseudoscience enthusiasts; the so-called Bosnian pyramids and the Ravne tunnels have been morphed into “New Age pilgrimage sites”. By June 2016, Osmanagić had completed an “archaeological park” at one of the hills, where he attracts volunteers who are constructing botanical gardens; meditation sessions have been held at the site. It has been noted that tourist traffic has aided the economy of the city of Visoko, located near the front of the war that destroyed so much of the country in the late 20th century.As of 2017, Osmanagić continued to make alterations to the hills and add to his marketing about them. His work at the time was based on private funding.

The hills are located near the town of Visoko, northwest of Sarajevo. The town was Bosnia’s capital during the Middle Ages, and ruins of a medieval fortress are located atop Visočica hill. Given the defensive strategic value of hilltop locations, other civilizations built facilities at this site: the fortress was built over an old observation post of the Roman Empire, which, in turn, had been constructed on top of the ruins of a further more ancient settlement.The hills are a type known as flatirons. Archaeological geologist Paul Heinrich of Louisiana State University has said that such formations are common throughout the world, for example, the so-called “Russian Twin Pyramids” in Vladivostok, and there are many in the nearby region.

In October 2005, Osmanagić and his supporters initiated a long-running media campaign to promote the pseudo-scientific belief that Visočica hill and the surrounding hills are an ancient pyramid complex. In an interview with Philip Coppens in Nexus (April–May 2006), Osmanagić suggested that they were most likely constructed by the Illyrians, who (according to Osmanagić) lived in the area from 12,000 BC to 500 BC. He has since argued that Visočica is an example of cultures building on top of other cultures. In 2017 Osmanagić was reported to have claimed that the structures date back 34,000 years.

In addition, Osmanagić claims that tunnels around the hill complex, which have been named Ravne tunnels, are an ancient man-made underground network.  They are claimed to be 2.4 miles (3.8 km) long. He claims to have found fossilised leaves in them dating back 34,000 years.

Osmanagić supports a number of fringe claims, saying he discovered “standing waves” at the top of the largest of the hills, waves which he ᴀsserts travel faster than light and prove the existence of a “cosmic internet” that allows for intergalactic communication.  He also promotes the idea of ancient astronauts and claims that human beings are the product of genetic engineering.

Osmanagić has given his own names to the hills. He has named the two largest hills as the “Pyramid of the Sun” and the “Pyramid of the Moon” (not to be confused with the genuine pyramids of the Sun and the Moon in Teotihuacan, Mexico). Other hills have been named by Osmanagić as the pyramids of “Love”, “the Earth”, and “the Dragon”.

Local authorities have funded his excavations, and authorized visits to the “pyramids” by school children, with guides telling them the hills are part of their Bosnian heritage. The site has become a tourist destination.

According to Osmanagić, the dig in 2006 involved an international team of archaeologists from Australia, Austria, Ireland, United Kingdom and Slovenia.  However, many archaeologists whom he named have stated they did not agree to participate and were never at the site. Osmanagić also claimed the support of an “Oxford archaeologist”, who was found to be an unqualified undergraduate. His foundation’s website claimed support of a British Member of Parliament; the name given was not that of any sitting member. 

Osmanagić claims that the direction of the hills reveals alignment to support ancient human cosmology. According to Enver Buza, a surveyor from Sarajevo’s Geodetic Insтιтute, the “Pyramid of the Sun” is perfectly oriented to the north. Osmanagić has said that the sides of the pyramid are oriented toward the cardinal points, and has claimed that this could not be produced by natural processes.

Osmanagić’s claims have also centred on alleged evidence concerning satellite pH๏τography, thermal analysis and radar detection. An article by Ian Traynor for The Guardian in 2006 reported that Osmanagić and his team alleged that their results from such research showed that the hills were not natural formations and that tunnels may exist inside the hills.

According to Osmanagić, his excavations have produced evidence of blocks that he claims may be part of a man-made outer surface. Osmanagić claims that these blocks are made of a concrete poured on-site that was stronger than today’s versions.