In the North-Western part of Bulgaria, between the town of Belogradchik and the village of Kara-oreshets, is the cave Kozarnika. Its total length is 128 m.

The cave is famous because of the unique discoveries made by scientists in the course of archaeological excavations. The first scientific expedition led by Nicholas Sirakova (Archaeological Institute, a unit of the Bulgarian Academy of Sciences, Sofia) and Jean-Luc Guadelli (Institute of Geology and prehistoric times, Bordeaux) was sent to Kozarnika in 1996. Since then, the Bulgarian-French research team made several interesting findings. Archaeological excavations found evidence of human culture during the late Paleolithic (37-34 centuries BC): the remains of butchered animals, primitive tools, etc. the Cave was inhabited in the middle Paleolithic, however, some findings point to a more ancient age.

Every year archaeologists penetrate into deeper layers of history with the aim to make an amazing discovery. Previously it was thought that the earliest humans arrived in Europe from Africa via Gibraltar. Evidence (traces of human activity, of which 800 thousand years), supporting this hypothesis have been found in Spain. However, in Kozarnika discovered phalanx of the human finger and the tooth, which are more than 1, 6 thousand million years. These artifacts may be evidence that the first humans set foot on the continent not through Gibraltar, and across the Bosphorus Strait in the Balkans.