If you’ve ever hiked through a quiet spruce forest and thought, “there’s probably a secret city under my feet,” first of all—excellent instincts. Second, welcome to the Owl Mountains (Góry Sowie) of Lower Silesia, Poland. There, a web of WWII-era tunnels snakes through granite and sandstone, like a hidden subway map drawn by a perfectionist with a jackhammer. This is Project Riese (“Riese” means Giant in German). It comprises seven unfinished underground complexes and a honeycomb of passages bored beneath hillsides and even beneath Książ Castle. Part industrial bunker, part enigma, and wholly sobering, Riese blends the thrill of discovery with the weight of memory. It’s a history that asks you to look closer, walk softer, and carry a flashlight you’re not afraid to drop.
This guide takes you through tunnels and onto ridgelines. It shows how to explore one of Europe’s most unusual WWII landscapes responsibly, practically, and with a touch of gallows humor. After all, if you can’t joke about your fogged-up hard hat, what can you joke about?
Where on earth is this—and what does it look like up top?
The Owl Mountains are in southwestern Poland, in the Central Sudetes. They are a range of rounded, forested peaks. The area has well-marked trails and lookout towers. The protected Owl Mountains Landscape Park covers over 80 km². This is classic hiking country. It features conifers, fast streams, and scenic views from Wielka Sowa, meaning ‘Great Owl,’ which is about 1,015 meters high. There is a 25-meter stone observation tower from 1906 that still watches over the ridgelines. The highlands look innocent from above, with moss, berries, and picnic benches. But if someone mentions there’s an elevator shaft under the castle in the valley, your maps might get confusing. Wikipedia+2dolnyslask.travel+2
How a “Giant” was born: the war comes underground
By late 1943, Allied bombing was chewing through German industry and leadership knew critical arms production and command infrastructure needed to hide—preferably under mountains. Under Albert Speer’s armaments ministry, with Organisation Todt coordinating the engineering juggernaut, work began in Lower Silesia on Project Riese. Its purpose remains partially obscure; surviving evidence points to a dual track: adapting Książ Castle as a leadership site while carving sprawling underground factory spaces into the Owl Mountains. The complexes were immense in ambition but uneven in completion—only a fraction ever received concrete lining. What is painfully clear is who did the digging: forced laborers and concentration-camp prisoners, many from the Gross-Rosen system. Wikipedia+1
Within this network, a specific set of subcamps—AL Riese—was created to feed labor to the tunnels. The Gross-Rosen Museum records that about 13,000 prisoners passed through these camps and an estimated 5,000 died—numbers that give weight to every dripping tunnel and steel anchor you’ll see today. Gross-Rosen
The map under the mountains: seven sites, three you can walk today
“Riese” wasn’t one caverns-and-catwalks lair; it was a cluster of sites. Some are mere stubs of tunnels; others hint at grand galleries. Today, several are open on guided routes; three of the most accessible are Osówka, Włodarz, and Rzeczka/Walimskie Sztolnie (often called the Walim Adits).
Osówka: The “Underground City”
Beneath Osówka Mountain (German: Säuferhöhen), a tunnel and hall grid stretches about 1.7 km. Chambers reach up to 8 meters high. You’ll see guard-room nooks, ventilation features, and mysterious hydraulic installations. Outside, foundations once held heating sheds that warmed cement bags in winter. Osówka markets multiple tour types: “historical,” “extreme,” and a longer “Expedition Riese,” each layering in interpretation. The complex is often described as the most developed of the mountain sites—“developed” meaning “the builders got the farthest before the war ended,” not “there’s a food court down there.” Bring warm layers; the underground climate is loyally 8–10 °C. Wikipedia+1
Włodarz: Boat through the dark
Inside Włodarz Mountain (Wolfsberg), galleries were cut one atop another, with ceilings collapsed between to create large halls—an engineer’s trick to widen volumes. Some sections flooded post-war, so tours can include a short boat ridethrough flooded tunnels (adventure meets damp socks). Włodarz remains raw: mesh bolting over rock, rough-hewn walls, and the eerie acoustics of a place never allowed to finish becoming whatever it was meant to be. Wikipedia+1
Rzeczka / Walimskie Sztolnie: The concise, potent introduction
The smallest of the trio at roughly 500 m of tunnels, Rzeczka (the Walim Adits) concentrates the story into a tight, vivid route: three parallel adits, concrete reinforcements in places, and galleries tall enough to swallow a house. This site doubles as a place of remembrance, and many visitors start here before tackling the longer, wetter, colder Włodarz and Osówka. Sztolnie Walimskie
Under the castle: Książ and its two levels of tunnels
Riese also reshaped Książ Castle (Schloss Fürstenstein), a palatial pile perched over a gorge like it’s auditioning for a Gothic novel. Below the courtyards, builders carved two underground levels—one shallow level accessible from the castle’s cellars and a deeper, more extensive system about 53 meters below. Parts were concreted, elevator shafts were sunk, and surface works (water reservoirs, pumping stations) sprouted around the estate. Documentation is fragmentary; what remains suggests they were constructing hardened spaces for high-level use and emergency sheltering, perhaps linked conceptually—if not physically—to the mountain complexes. Today, guided tours explain the theories and human cost of this transformation. Wikipedia+2Zamek Książ+2
Who built it? Camps, companies, and the cost of speed
Riese’s pace and scale demanded logistics: narrow-gauge railways to move spoil, road-building in rough terrain, and a revolving door of German construction firms under the umbrella of the Silesian Industrial Company(Industriegemeinschaft Schlesien). But the system’s engine was forced labor. Subcamps named for local topography—Wolfsberg (Włodarz), Säuferwasser (Osówka), Falkenberg (Sokolec/Gontowa)—supplied men to swing the drills, haul timbers, pour concrete, and dig drainage ditches in bitter conditions. The Gross-Rosen Museum preserves a grim roll call of these camps and summarizes their fates in early 1945: evacuations on foot toward Flossenbürg, Mauthausen, and Bergen-Belsen; hospital barracks left behind to be liberated days later. Gross-Rosen
So…what was Riese meant to be?
Short answer: a hybrid. The most balanced reading of surviving engineering and planning points to Książ being adapted as a leadership facility, while the mountain tunnels were pushed toward dispersed underground manufacturing—a logical response to bombing. Walk the galleries and you’ll notice the difference: the castle’s concrete tunnels feel designed for people, lifts, and protected transit, while the mountain chambers read like production shells and utility spaces. The ambiguity is part of Riese’s magnetism; in a landscape of rumor and myth, the rock is oddly honest—look at the dimensions, the ventilation, the water handling, the rail spurs—and it tells you what it wanted to be. Wikipedia
The legend that won’t quit: the “Nazi gold train”
No story about Riese is complete without the gold train legend: an armored train laden with treasure that vanished into a tunnel near Wałbrzych as the Red Army closed in. In 2015, two treasure hunters announced radar images that, they claimed, proved a train was buried by the tracks. The media went full Indiana Jones; officials cordoned off woodland; the army checked for mines. Then scientists reported there was no train; later digs found nothing but natural geology. The saga bubbles up every few years—there were fresh headlines again in 2025 about new search permissions—but the verdict remains the same: no confirmed train. If you want gold in these hills, hike in October; the beech leaves are priceless. Notes From Poland+3The Guardian+3Reuters+3
Walking through history: what it feels like underground
A Riese visit is a sensory switch. One moment you’re on a forest track with a woodpecker for company; the next you’re pulling on a helmet and following a pool of LED light into someone else’s unfinished blueprint.
- Sight: Rock faces perforated by drill marks; wire mesh holding back time; boxy recesses where transformers or ventilation fans likely sat; in places, elegantly poured concrete arches that whisper “this part mattered.”
- Sound: Drops of water that echo like metronomes; the glide of a boat at Włodarz; a guide’s voice naming the subcamp that supplied the day’s workforce in 1944.
- Smell: Wet stone and oil; occasionally the mineral tang of standing water.
- Touch: Cool handrails; a soft grit on your palms if you steady yourself against the wall (gloves help).
It’s compelling—but it lands hardest when you connect the engineering to the people: the men in striped uniforms trudging to adits like Säuferwasser or Wolfsberg, the Arbeitszüge (work trains) rattling in with timber, cement, rebar, and hope—or something like it—that the roof would hold. The best guides don’t tilt into sensationalism; they focus on labor systems, survival, and the political logic that drove a mountain to be turned inside out. Gross-Rosen
Pair it with the summit: nature + history in one day
Because the Owl Mountains are eminently hikeable, you can mix underground and overground in the same day:
- Morning: Walim Adits (Rzeczka) for a concise, well-interpreted overview.
- Lunch: Walim or Jugowice—local kitchens do pierogi that defeat the chill better than any fleece.
- Afternoon: Hike up to Wielka Sowa for views (and that 1906 tower). On clear days you can see across the Kłodzko Valley and as far as the Krkonoše.
- Next day: Osówka or Włodarz for longer, more rugged underground routes; finish at Książ Castle to stitch palace to tunnel. dolnyslask.travel
Practical guide: how to visit
The cluster is centered around Walim, Głuszyca, Jugowice, and Wałbrzych. Additionally, the nearest major city and airport is Wrocław, which is about 1.5 to 2 hours away by car. Moreover, regional trains to Wałbrzych, along with local buses and taxis, provide alternative transportation options.Once in the area, sites are a short drive apart; hikers can link them on forest roads and marked trails (but mind the daylight—this isn’t a place to test your night-navigation swagger).
Which site first?
- New to Riese? Start with Rzeczka/Walimskie Sztolnie—compact and interpretive.
- Want more scale? Osówka offers variety in route styles (historical vs. “extreme”).
- Chasing atmosphere? Włodarz adds boats and broad, raw chambers. Sztolnie Walimskie+2osowka.eu+2
Tours & tickets. All three operate guided routes (often in Polish, with materials/QRs in English and German at some sites). Schedules and offerings change seasonally; check the official pages for hours and to pre-book during weekends/holidays. (Bonus tip: Książ Castle sells combined castle-plus-underground tickets—handy if you’re building a tight day.) osowka.eu+1
What to wear. Underground temps hover around 8–10 °C year-round. Dress like it’s early spring in a refrigerator: base layer, warm mid-layer, waterproof jacket. Sturdy shoes with grippy soles—parts can be slick. Helmets are provided where required; bring a headlamp if you like extra light for photos (but obey no-flash rules and your guide).
Accessibility & age. Expect uneven ground, steps, low ceilings in places, and the boat segment at Włodarz. If you’re traveling with kids or anyone sensitive to confined spaces, Rzeczka is the least claustrophobic starting point. Sztolnie Walimskie
Photography. Low light means grainy shots unless you have a tripod (often not allowed) or fast lenses. Honestly, the best photos are sometimes topside—trailheads with WWII concrete relics, the dam structure at Osówka, or the castle’s dramatic clifftop façade.
Respect. These are sites of forced labor and death. Most tours mark this explicitly; follow local commemorative practices and keep voices low. If a guide asks for silence at a plaque, it’s not a theatrical beat—it’s for the names behind the numbers. Gross-Rosen
Field notes for the travel-historian (a.k.a. you)
- Notice the ventilation. Large, smooth concrete tunnels with consistent arching suggest human occupancy; rough-cut halls with evidence of crane rails or foundations hint at industrial use.
- Hydraulics are clues. At Osówka you’ll see dams and pipework; in mountainous factories, water management was as important as power. Wikipedia
- Follow the rail. Narrow-gauge lines once threaded spoil tips and material depots to railheads like Olszyniec; surface traces still appear as berms or oddly level corridors in the woods. Wikipedia
- At Książ, think vertical. Elevator shafts and multi-level connections show planners anticipated rapid protected movement—another tell that the castle had a distinct function from the mountain halls. Wikipedia
Frequently myth-asked questions (FMAQ)
Did Hitler ever use Riese? There’s no credible evidence he did; the complexes were unfinished at war’s end. The project’s purpose remains partially uncertain, but scholarly consensus today leans toward leadership adaptation at the castle and underground production in the mountains.
Is the gold train real? The 2015–2016 frenzy ended with no confirmed train, despite ground-penetrating radar hype and an excavation. Fresh claims surface periodically; it’s part of local lore. Pack curiosity, not a metal detector. The Guardian+1
How many people died here? The Gross-Rosen Museum estimates that around 5,000 of the approximately 13,000 prisoners in AL Riese perished due to disease, malnutrition, overwork, and evacuation. This starkly highlights the human toll behind every engineering fact.Gross-Rosen
Sample 2-day itinerary (history lover + hiker)
Day 1 – The Big Picture
- Morning: Rzeczka (Walim Adits) guided tour for orientation.
- Lunch: Pierogi and hot soup in Walim.
- Afternoon: Drive to Książ Castle; tour the palace and underground levels.
- Evening: Wałbrzych old town stroll; rest.
Day 2 – Into the Giant
- Morning: Osówka—choose “Historical” or “Expedition Riese” route.
- Lunch: Głuszyca café.
- Afternoon: Włodarz tunnels with boat section; coffee at the museum hut.
- Golden hour: Short hike to a ridge viewpoint or, if legs allow, up Wielka Sowa for sunset from the 1906 tower. dolnyslask.travel+3Zamek Książ+3osowka.eu+3
Final thoughts: why Riese matters
Riese is powerful because it’s unfinished. Most WWII sites are frozen in a finished function: a bunker that served, a camp that operated, a battlefield that raged. Here, you walk through intent. You see what total war wanted to become under a mountain—and you see it stopped. That gap is instructive. It reminds us how quickly industries of violence recruit landscapes, and how much labor—usually coerced—stands behind “impressive” engineering.
Come for the mystery. Stay for the mountain air. Leave with better questions.
Sources & further reading
- Concise overview of Project Riese purpose, planning under Speer/Organisation Todt, and technical details of Osówka, Włodarz, and Rzeczka complexes. Wikipedia
- Gross-Rosen Museum on AL Riese: list of subcamps, estimated 13,000 prisoners and ~5,000 deaths, evacuation fates. Essential for understanding the human cost. Gross-Rosen
- Książ Castle official pages: history and the castle tunnels tours; interpretation of their intended function. Zamek Książ+1
- Walimskie Sztolnie (Rzeczka) official site for visitor information and the memorial focus of the adits. Sztolnie Walimskie
- Owl Mountains Landscape Park background and context; Wielka Sowa tower details from the Lower Silesian Tourist Organization. Wikipedia+1
- Gold train legend: reporting on the 2015–2016 wave and scientific debunking; 2025 note on renewed, unproven searches.
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