Project Riese

The air changes first. A few steps inside the tunnel, the warmth of the day falls away and a cool, damp stillness settles on your skin. Water drips somewhere in the dark. The walls are raw grey rock, rough and uneven, marked by drills and blasting. Underfoot, the ground is wet and gritty. You are standing inside the Owl Mountains of Lower Silesia, in one of the largest unfinished construction projects of the Second World War.

This is Project Riese. The name is German for giant, and the scale explains the choice. Across the mountains around Wałbrzych, Nazi Germany began digging a network of tunnels, halls, and shafts deep into solid rock. The work started in 1943 and continued until the final months of the war. It was never completed. What remains today is a scattered set of underground complexes, each one a fragment of a plan that nobody fully understands.

That last point surprises many visitors. Historians still do not agree on what Project Riese was meant to be. Some documents and witness accounts point toward a headquarters for Hitler and the top leadership. Others suggest underground factories, safe from Allied bombers, for producing weapons. It may have been both, or the plan may have shifted as the war turned against Germany. Many records were lost or destroyed, so the purpose remains an open question.

The project was not one tunnel but several separate sites. The best known have Polish names today: Osówka, Włodarz, Rzeczka, Sobień, Jugowice, and Soboń, along with tunnels beneath Książ Castle on the edge of Wałbrzych itself. Some of these sites are open to visitors on guided routes. Others remain closed, partly flooded, or only reachable by specialists. Each complex has its own character, from long concrete-lined halls to narrow galleries of bare stone.

The rock around you is hard and ancient. The Owl Mountains are made largely of gneiss, a dense, banded stone formed under great heat and pressure. Look at the walls in the lamplight and you may see faint stripes running through it. Cutting into this material by hand, with drills and explosives, was slow and brutal work. That difficulty shaped everything about this place, including the human cost.

And the human cost was enormous. The tunnels were dug by forced labour. At first, the workers included prisoners of war and forced labourers from occupied countries. Later, thousands of concentration camp prisoners were brought here, many of them Jewish men transported from other camps. They were held in a network of subcamps linked to the Gross-Rosen concentration camp, one of the main camps in this region.

Conditions were terrible. Prisoners worked long shifts in cold, wet tunnels, with little food and poor clothing. Accidents, disease, exhaustion, and violence killed many of them. The exact number of deaths is uncertain, and historians give different estimates. As you walk through these passages, it helps to remember that every metre of rock was removed by people who did not choose to be here. This is a construction site, but it is also a place of suffering.

In 1944, responsibility for the project passed to Organisation Todt, the large Nazi engineering and construction body that built fortifications and military works across occupied Europe. Work sped up. More labour was brought in, and more concrete was poured. Yet by early 1945, the Soviet Red Army was advancing from the east. The digging stopped, the workers were moved or marched away, and the tunnels were left as they were.

That sudden stop is why the sites look the way they do. In some halls, smooth concrete walls rise beside sections of rough, blasted rock. Steel reinforcing bars stick out where pouring was never finished. Piles of broken stone lie where they fell. In places, you can see the outlines of planned rooms that were never fully cut. It feels less like a ruin and more like a building site paused in the middle of a working day.

Above ground, the forests hide much of the story. On walks around the complexes, people find concrete foundations, the remains of railway lines, old water reservoirs, and spoil heaps of excavated rock, now covered with moss and trees. These traces show how large the surface operation was. Roads, rail links, and camps once filled these hills. Today, the sound is mostly wind in the beeches and spruces, and birdsong.

Because so much is unknown, Project Riese has attracted a great deal of speculation. Locals and treasure hunters tell stories of sealed tunnels, hidden archives, and lost valuables. The most famous is the legend of a Nazi gold train, said to be buried somewhere near Wałbrzych. In 2015, a claim about this train caused a media sensation and an excavation followed, but nothing was found. These tales are folklore, not documented history.

What is documented is enough to fill this space with weight. Engineers, survivors, and historians have pieced together much of what happened here, and research continues. Guided tours today often combine history with the physical experience of the tunnels: the cold, the echo of your own footsteps, the narrowness of some passages. Bring a warm layer and sturdy shoes, even in summer. The underground temperature stays cool all year.

As you head back toward daylight, notice how the sound changes. The drip of water fades, and the noise of the outside world returns, voices, birds, the wind in the trees. Take a moment at the entrance. Behind you lies a project built for war and finished by no one. Ahead are the green hills of the Owl Mountains. Both belong to this landscape, and both are worth carrying with you as you walk on.