Sasha

Recommended for MTB or gravel bikes with good tires. Moderate climbs and technical sections included. The route starts on bike paths (about 6 km of asphalt) and quickly transitions onto rough, rocky roads unsuitable for a standard city bike. Later sections improve slightly but remain uneven and challenging. In some spots, you may need to carry your bike for a few meters. The highlight of the route is the large and impressive Secret Object A – Southern Tunnel, part of an unfinished Cold War-era railway connecting Varna and Burgas. Built in the 1950s for military-strategic purposes, it includes tunnels, bridges, and earthworks that are still visible today. Notes: • Riding alone is not recommended. • Avoid going in the dark. • Be cautious: wild animals may appear, though unlikely. • If entering the tunnel, go only in a group, with bright lighting and proper footwear. • To access the second floor (with open window spaces), enter the main arch, turn right, and climb the steep stairs carefully. • To reach the top (no roof, just the structure itself), follow the trail to the right of the building—do so at your own risk.