Goldbacher Stollen

Goldbacher Stollen, known in English as the Goldbach Tunnels, is an underground tunnel complex excavated in the Molasse rock between the Überlingen district of Goldbach and the town of Überlingen on the northern shore of Lake Überlingen, part of Lake Constance. It was constructed under Nazi Germany between June 1944 and April 1945 as a planned underground relocation facility for strategically important armaments production from Friedrichshafen, a major industrial and military center that had been repeatedly attacked by Allied bombing. The project arose from Germany's late-war effort to disperse weapons and aircraft-related manufacturing into sites less vulnerable to air raids. Friedrichshafen was home to companies including Luftschiffbau Zeppelin, Maybach-Motorenbau, Zahnradfabrik Friedrichshafen, and Dornier Flugzeugwerke. After extensive damage to the city and its factories, the German fighter-production authorities ordered underground facilities in the Überlingen area and at Hohenems in Vorarlberg. Überlingen was selected because it lay on the Stahringen–Friedrichshafen railway and offered relatively accessible Molasse rock, which could be excavated more easily than harder geological formations. The construction project was code-named Magnesit. The Munich engineering firm Arno Fischer led the design, Siemens-Bauunion acted as main contractor, and the Organisation Todt supervised the work for the armaments administration. The original plan called for approximately 100,000 square metres of underground space, but this was reduced to about 40,000 square metres. Maybach-Motorenbau, Zahnradfabrik Friedrichshafen, and Dornier were designated as intended users, with each company allocated a longitudinal tunnel and rail access. The complex ultimately comprised 17 cross tunnels, eight entrances, and more than four kilometres of underground passages. Individual sections varied considerably in width and height, and some junctions were enlarged into hall-like spaces. Industrial equipment was installed in parts of the tunnels, but the war ended before regular production is thought to have begun. The site is inseparable from the history of concentration-camp forced labor. Prisoners from the Überlingen-Aufkirch subcamp of Dachau were compelled to perform dangerous excavation and spoil-removal work in long shifts, generally without adequate safety equipment. The camp held approximately 700 prisoners and was guarded by SS personnel. Prisoners used pneumatic drilling equipment, handled explosives, and transported excavated material to the lakeshore. Rockfalls, blasting accidents, malnutrition, abuse, and exhausting conditions caused numerous injuries and deaths. Documentation identifies 243 prisoners who died during the construction period, although the precise circumstances of every death are not known. Construction ended in April 1945. As French forces approached, the surviving prisoners were evacuated to the Munich-Allach concentration camp on April 20. After the war, the tunnels were looted before French occupation authorities sealed entrances and sections of the complex with explosives in 1947. Later, the federal government assumed ownership under postwar property legislation. A new access point was created in the 1960s, and sections were reinforced with shotcrete during the 1980s. Goldbacher Stollen has had several postwar uses. Parts of the complex have been used for seasonal storage of caravans and boats, and the tunnels temporarily served as a morgue during the identification process following the 2002 Überlingen mid-air collision. Since 1981, guided tours have provided public access to the historical site, and a documentation center has operated there since 1996. The site's contemporary identity is primarily educational and commemorative rather than commercial. Memorials, exhibitions, tours, publications, and public events present the history of the forced laborers, the concentration-camp subcamp, the armaments project, and the site's later history.

The Goldbach Tunnels were created during the final phase of Nazi Germany's wartime industrial dispersal program. Friedrichshafen, on the northern shore of Lake Constance, was a major center for aircraft, engine, gear, and other military production. Repeated Allied air raids had devastated the city and damaged or destroyed many of its factories. In response, the German authorities sought underground or otherwise concealed locations in which production could continue. On May 1, 1944, the fighter-production authorities ordered tunnel projects at Überlingen and Hohenems. The Überlingen site benefited from its proximity to the railway linking Stahringen and Friedrichshafen and from the excavability of the local Molasse rock. Work began in early June 1944 under the code name Magnesit. Arno Fischer of Munich was responsible for engineering, Siemens-Bauunion served as the principal contractor, and the Organisation Todt provided supervisory support. The planned underground area was initially extremely ambitious, covering approximately 100,000 square metres, but the target was later reduced to around 40,000 square metres. Maybach-Motorenbau, Zahnradfabrik Friedrichshafen, and Dornier were identified as intended industrial occupants. The design provided separate longitudinal tunnel areas and rail connections for the companies. The construction effort relied heavily on prisoners from the Überlingen-Aufkirch concentration-camp subcamp, which belonged to the Dachau concentration-camp system. The subcamp was documented by September 1944 and housed roughly 700 prisoners at a site in Aufkirch, around 1.5 kilometres from the excavation area. Approximately 25 SS guards oversaw the prisoners under commandant Georg Grünberg. Prisoners worked 12-hour shifts, drilling into the rock with pneumatic tools, removing spoil in tipper carts, and taking the material to the lakeshore. They generally lacked basic protective equipment and were exposed to rockfalls, blasting hazards, exhaustion, hunger, cold, and violence. The tunnel layout eventually included 17 cross tunnels, eight entrances, and over four kilometres of passageways. Widths ranged from roughly two to 25 metres and heights from about two to ten metres. Some intersections were expanded into larger halls. Industrial workers from the designated Friedrichshafen companies began installing machinery in completed sections. Accounts from former company employees and survivors indicate that barriers separated prisoners from industrial personnel and that prisoners were not allowed to shelter behind those barriers during blasting. Survivor testimony describes frequent collapses, injuries, deaths, and abusive treatment. Boris Kobe, a Slovenian prisoner, later represented the labor regime and camp violence in an illustrated tarot-card series. The facility was never fully realized as an operating armaments plant. Construction ended in mid-April 1945, shortly before French forces reached Überlingen. On April 20, the remaining prisoners were evacuated to Munich-Allach. At least 243 prisoners died in connection with the project, although the surviving record does not establish the precise cause of every death. Early victims were buried in Überlingen, while later bodies were cremated in Konstanz or buried in a nearby forest. Many identified victims are commemorated at the Birnau concentration-camp cemetery. The immediate postwar history was unsettled. The tunnels were looted, after which French occupation authorities blocked entrances and sections with explosives in 1947. Around 3.6 kilometres remained accessible, including portions passable by vehicles. Ownership later passed to the federal government under postwar property arrangements. A maintenance entrance was added in the 1960s, when the possibility of using the complex as an air-raid shelter was also discussed. Between 1983 and 1989, sections were stabilized with sprayed concrete. For a period, the tunnels were used for winter storage of caravans and boats, a use that generated public controversy in 1994. They also played an emergency role after the 2002 Überlingen mid-air collision, when the complex was used temporarily for victim identification. Since 1981, the site has offered regular guided tours, and a documentation center has operated since 1996. The location has hosted remembrance events, including a 2005 concert marking the 60th anniversary of the prisoners' liberation. In preparation for the 2021 Überlingen State Garden Show, the former lakeshore spoil area was integrated into the Uferpark, and a memorial installation using a recovered tipper cart was placed near the tunnel entrance. Today, Goldbacher Stollen is principally a place of historical education, local memory, and commemoration of the prisoners subjected to forced labor.

• 2021

  Memorial integrated into the State Garden Show landscape

  [1]Goldbach Tunnelsen.wikipedia.org

  The former lakeshore spoil area becomes part of Überlingen's State Garden Show grounds, with a tipper-cart memorial installation.

• 1996

  Documentation center established

  [1]Goldbach Tunnelsen.wikipedia.org

  A documentation center opens to interpret the tunnel project, forced labor, and the history of the Überlingen-Aufkirch camp.

• 1981

  Regular public tours begin

  [1]Goldbach Tunnelsen.wikipedia.org

  The tunnel complex begins receiving visitors through regular guided tours.

• 1947

  Sections are sealed after the war

  [1]Goldbach Tunnelsen.wikipedia.org

  French occupation authorities close entrances and parts of the tunnel system after a period of looting.

• 1945

  Construction stops and prisoners are evacuated

  [1]Goldbach Tunnelsen.wikipedia.org

  Work ends in April before industrial production begins, and surviving prisoners are evacuated to Munich-Allach on April 20.

• 1944

  Armaments authorities order the Überlingen tunnel project

  [1]Goldbach Tunnelsen.wikipedia.org

  Following heavy bombing of Friedrichshafen, German wartime authorities designate Überlingen as a site for underground relocation of strategically important industrial production.

• 1944

  Construction begins under the code name Magnesit

  [1]Goldbach Tunnelsen.wikipedia.org

  Excavation begins in June under Arno Fischer, Siemens-Bauunion, and Organisation Todt supervision, with forced labor supplied by the Überlingen-Aufkirch subcamp.

• 1944

  Überlingen-Aufkirch subcamp documented

  [1]Goldbach Tunnelsen.wikipedia.org

  The concentration-camp subcamp, holding approximately 700 prisoners, is documented as part of the labor system supporting the tunnel construction.

A local historical monument, documentation center, and remembrance site focused on Nazi-era armaments production, concentration-camp forced labor, and the postwar history of the tunnel complex.

• Historical tourism · 1981

  Guided tunnel tours

  Guided visits introduce the surviving underground passages and explain their wartime construction, intended armaments use, forced-labor system, prisoner deaths, and postwar development. The tours form the site's principal public-facing offering and connect the physical environment with documentary and memorial interpretation.

• Museum and historical interpretation · 1996

  Documentation center

  The documentation center provides an institutional setting for presenting the history of Goldbacher Stollen and the Überlingen-Aufkirch concentration-camp subcamp. Its subject matter includes the armaments relocation program, the engineering and construction process, prisoner testimony, the names and fate of victims, and the complex's postwar uses.

• 2021State Garden Show remembrance installation

  Germany

  For the Überlingen State Garden Show, the site organization and associated documentation groups incorporated a memorial installation into the redeveloped lakeshore area. The installation, designed by landscape architect Marianne Mommsen, uses a recovered tipper cart placed on rails near the tunnel entrance.

  Outcome. The former spoil landscape was incorporated into the Uferpark while retaining a visible reminder of the forced labor used to create the tunnels.

  Source
• 200560th-anniversary commemorative concert

  Germany

  A remembrance concert was held inside the tunnels on May 8 to mark six decades since the liberation of the prisoners. The Latvian State Choir performed under Māris Sirmais, including works by Henryk Górecki.

  Outcome. The event used the historic structure as a venue for public remembrance and cultural commemoration.

  Source

• 1981

  Opening of the site to regular guided visitsOther

  Background

  The former wartime industrial site had remained physically present but required public interpretation and controlled access.

  Action taken

  Regular guided tours were introduced, framing the tunnels as a historical and memorial site.

  Aftermath

  Public access and historical education became central to the site's continuing role.

  Source

• 1944

  Underground relocation of Friedrichshafen armaments productionStrategy

  Background

  Allied air raids had severely damaged Friedrichshafen and its military-industrial factories. German authorities sought to disperse production into protected underground locations.

  Action taken

  Authorities commissioned the Überlingen tunnel project and planned separate production areas for Maybach-Motorenbau, Zahnradfabrik Friedrichshafen, and Dornier.

  Aftermath

  The complex was substantially excavated and partly fitted with machinery, but the war ended before regular production is believed to have started.

  Source

1. 1Goldbach Tunnelsen.wikipedia.org
2. 2Official Goldbacher Stollen documentation center websitestollen-ueberlingen.de