Osówka Underground City

To this day nobody knows for certain what the concrete halls and tunnels cut into Osówka mountain from 1943 were meant for. Some say a secret headquarters for Hitler was being built here, others that it was underground armaments factories. Osówka Underground City, a kilometre north of the village of Sierpnica, is the longest publicly accessible section of the Riese complex (German for "giant") in the Owl Mountains, and one of the places where you can see the mystery up close.

History: built in secret

Work began in mid-1943. A system of concrete corridors, fortifications and halls was cut into Precambrian gneiss, and the purpose was kept strictly secret. The labour came from forced workers and prisoners of the Gross-Rosen concentration camp; a sub-camp, AL Säuferwasser, operated in the Kłobia stream valley at the foot of the mountain. The underground section has about 1,700 m of tunnels in three adits, the longest about 450 m. In one of them brick dams hold water inside the tunnel.

The surface part of Osówka is considered the most advanced of all the Riese sites. Two buildings are especially striking: the "Casino", 50 m long, with window openings and a roof cast as a basin that was to be filled with soil and plants, and the "Power Plant" – a concrete block of tanks and chambers reached through hatches with steel rungs.

Tour routes

• Historical route – the main one, with fixed lighting, 1,200 m, about 60 minutes. It passes concrete guardrooms, a hall with formwork, a service corridor and huge chambers in the gneiss. Along the way: documentary films, holograms (including "Italian miners at work") and display cases with equipment found during exploration in 2008. From age 5.
• "Post-war stories – extreme" route – 1,500 m by torchlight only, including a crossing of a flooded corridor in a leaky boat and walkways that are partly under water. The guide talks about uranium prospecting in 1953 and post-war expeditions. About 70 minutes, from age 8, only as an add-on to the historical route.
• Retro route – the main tunnels in dim torchlight, as on the first expeditions decades ago, before permanent lighting was installed.
• Educational route for families with children and a Path of Remembrance dedicated to the prisoners of Osówka.

Prices and hours (as of October 2026)

Tours run daily, always with a guide, at fixed entry times: 10:30, 11:00, 12:00, 13:00, 14:00, 15:00, 16:00 and 17:00 (these may change when it is busy). Tickets for the historical route are sold on site without booking – at least 30 minutes before the tour. Prices: historical route PLN 40 (reduced PLN 33), extreme PLN 45 (PLN 40), retro PLN 35 (PLN 30), combined historical + extreme ticket PLN 70. The extreme and retro routes must be booked by email.

Tripto tip

• It is always cold underground – bring warm clothes and sturdy, waterproof shoes, plus a spare pair for the extreme route.
• Don't trust your satnav: the operator recommends the tarmac road via Głuszyca, Kolce and Sierpnica; the side roads suggested by GPS are narrow and can be impassable in winter.
• Without a car: take the train to Głuszyca, walk 900 m to the transport hub on ul. Łukasiewicza and catch the minibus (on weekdays at 9:15, 12:45 and 14:45).
• Parking and toilets are free, and cards are accepted. Dogs cannot go underground, but there are free kennels on site.
• Combine Osówka with other Riese sites in the Owl Mountains for a full day out.