The Underground City of Osówka – Project Riese 


Project Riese (Giant) is one of the most mysterious construction projects of II WW. It was conducted in the region of the Owl Mountains by Nazi Germany. Even now, so many years after the II WW, no one is sure what the exact purpose was; was it quarters for the Supreme Command of the Third Reich, an underground laboratory, a factory for constructing the atomic bombs? The construction was never finished, the documents were destroyed, and what remains today is just a number of constructions sites across the Owl Mountains. Currently, four objects are open to visitors: OsówkaWłodarzWalimskie Drifts, and the Książ Castle, but there are many more both discovered and undiscovered.


Osówka, situated on the slope of Mount Osówka (707 m above sea level), was a second complex we got to visit on our tour. It is the second-largest complex of underground military buildings of the Riese project. The Underground City of Osówka consists of about 1700 m of narrow corridors intersected by halls and side passages. There are three tunnels, and tourists can see two of them. Osówka also has the most extensive and best-preserved system of terrestrial objects on the surface of the mountain. So if you have some time, go for a small hike and check it out.


Most of the pathways in the complex are still in a raw state, with only corridors drilled; however, some of the chambers retained wood forms, as they were prepared to be filled with concrete, and some passages were already finished. It was pretty remarkable to see the stages of development, from just a hole in solid rock to the double-layered corridor where a car could drive through, with space for pipes above our heads.

On top of that, throughout the tour, there were many multimedia stations where we watched short documentaries and visualizations. Some of them even had English subtitles making my life as a life translator so much easier! Interestingly, the multimedia tour in the Underground City of Osówka won this year (2021) the Audiovisual Project of the Year title in the “Education” category. 

If I were to chose only one of the complexes to visit, I would pick Osówka. It was the most foreigner-friendly of them all (by incorporating subtitles in the videos). The guide did not allow us to record the animations but taking pictures while walking was fine. It is a pretty big complex, showcasing different stages of the underground’s development. Plus, if you are more into adventure, there is also an extreme tour with the boat in the darkness. To sum up, it was the best mix of everything. 

There are three types of tour: 

  • Historical – which takes around an hour and is a default route you don’t need pre-booking for (unless you don’t want to wait too long). Following the Historical Route, you will see methods of drilling underground tunnels, different stages of the construction, guardhouses, photos of the external buildings, exhibits, armaments, equipment, halls with original formwork, and technical solutions of the object. 
  •  Extreme – takes around 70 -80 minutes. It is similar to the historical route except that the group takes a detour at some point, hops into a small boat, and crosses the flooded corridor in total darkness (or with a flashlight if you remember to take it). It is recommended to either take spare pair of shoes or risk it and be careful as you will cross the water both in the boat and by plank bridges, and you might step in the water. We didn’t manage to participate in this one as you need to pre-book it ahead of time, and I suck at planning 😛 
  • Expedition – taking around 90 min, covers the largest part of the complex and includes a look at some of the ruins at the surface. 

Useful tips

  • There is a free parking spot close by
  • Foreigners can rent an audio guide.
  • Some of the audiovisuals have English subtitles.
  • If you want an Extreme or Expedition route, pre-book it online and bring a torchlight.
  • Bring warm clothes as temperature oscillates at around 5C
  • For more info, check out the official site

A short history of the Riese Project

In 1943, after many German cities were air-raided and the tide of war started to change, Hitler ordered the undertaking of a massive, top-secret underground complex known as Project ‘Riese’ (Giant). The work on that project lasted until the last days of the war in 1945, where it got abandoned only when it became painfully clear for Nazis that they would lose control over that area. They boobytrapped the corridors and exploded the entrances so no one would be able to access them. Because they fled in a hurry, they left countless building materials, cement bags, aggregates, cables, and the foundations of unfinished ground structures in the forests of the Owl Mountains. Even today, if you take a walk through the forest paths, you can notice the remains of it. 

The project itself was humongous; imagine that for the Riese project alone, more concrete was used than was allocated in 1944 for the whole population to construct air-raid shelters. It was estimated that over two million cubic meters of rock would need to be blasted out of the Owl Mountains to complete this massive underground city. 

To dig the tunnels, Nazis used forced laborers from the Gross-Rosen concentration camp located in the nearby village. Most of them were Polish, Hungarian, and Italian Jews. What is horrifying is the fact that, on average, the prisoner used for digging the tunnels lasted around three to four months. This was due to several factors: the inhumane conditions they had to withstand with an unproportionate amount of hard work and almost no food (the concentration camp motto was Vernichtung Durch Arbeit (‘Extermination Through Work’)). They had to dig in gneiss rock, which has the same hardness as steel while using only basic tools. And the temperature in the shafts was around 5C with high air humidity, causing the small pieces of clothing they had left to be wet almost immediately.

To speed up the project, laborers mined from different locations concurrently. It was planned to eventually connect all those sections in one extensive system of tunnels, but the sudden end of war stopped the construction. Even though the project is not finished, with the varying condition of tunnels, it is still a place worth visiting and commemorating all the victims of war. 


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