Kozarnika is a cave in the hills about 5 km northeast of Belogradchik, notable as one of the most important prehistoric sites in Europe. Excavations since the 1970s have uncovered human remains and tools dating back over a million years, along with evidence of habitation through multiple Stone Age periods. The finds are scientifically significant even if the cave itself is relatively modest in size.
The cave is open to visitors, though access can be limited outside peak summer season — it is worth checking locally before making the trip. The drive from Belogradchik passes through pleasant rolling countryside and can be done by car or, for the fit, by mountain bike. Combine it with a return via a different road for a loop through the Belogradchik hills.