The territory of modern Bulgaria has been inhabited since deepest antiquity. Over the past several years, the archaeological excavations in the Kozarnika Cave in Northwestern Bulgaria have uncovered remains of a culture from the oldest (presently known to us) human inhabitants of the Old Continent: Homo erectus. The age when this species inhabited a comfortable cave in the mountains was approximately 1.4—1.1 million years ago.
While no masterpieces of cave interiors (similar to those in Spain and France) have been discovered in Bulgaria, the country has a multitude of interesting caves, where evidence of the material culture of Paleolithic humans has been discovered. Some of them (for example, Bacho Kiro Cave near Dryanovo) offer a well-established tourist infrastructure.