The highest peak is named Ruen (Руен, 2251 m), which constitutes the main orthographic knot on the very border between Bulgaria and North Macedonia. It has a prominent volcanic relief made of conic peaks and volcanic tuff and is rich in polymetal ores. There are many legends about the origin of name Osogovo, but the most famous one is that the area was briefly settled by Transylvanian Saxons miners who were mining gold and silver in the region in the past.