Pirin Mountains, 6 days.

Part of the E4, the Pirin Traverse follows the high ridge of the Pirin Mountains, south of Sofia. The trail can be walked from hut to hut, ending in the village of Melnik, close to the Greek border. Among the traverses is the popular Koncheto Ridge, a 1500 m long karst bridge at about 2800 m high between two peaks, well secured with steel ropes on exposed spots. Traversing the Pirin Mountains takes 6 days. If you plan to walk the E4, start in Sofia and walk south via the Vitosha, Verila, Rila and Pirin Mountains.