Reimahg Factory
Deep in the rolling hills of Thuringia, Germany, lies a mountain once hollowed out in secrecy to house one of the Third Reich’s most ambitious and desperate wartime projects. Known as the REIMAHG—short for Reichsmarschall Hermann Göring Werke—this underground factory was intended to produce Germany’s first operational jet fighter, the Messerschmitt Me 262, a revolutionary aircraft that had the potential to turn the tide of World War II. The story of how this hidden tunnel complex came into being is one of human endurance, engineering ambition, and the chilling consequences of war.
As Allied bombing raids intensified in 1944, Hitler and his high command sought ways to protect their most valuable industrial assets. Factories on the surface had become vulnerable targets, and the production of the Me 262, a plane that could outrun any Allied fighter, was considered critical. In response, Hitler ordered a number of key facilities to be moved underground, into mountains and hills, away from the reach of enemy bombers. One of the sites selected was the Walpersberg mountain near the town of Kahla in central Germany.
The task of transforming the mountain into a jet factory fell to a consortium of German engineers, architects, and the Nazi Organisation Todt, which specialized in large-scale construction projects. The mountain was to be tunneled and converted into a vast subterranean complex capable of assembling the Me 262 in secrecy. The REIMAHG facility would eventually include miles of tunnels, massive caverns for assembly lines, storage areas, and even systems for transporting finished aircraft to the surface.
To accomplish this, the Nazis mobilized a workforce of roughly 12,000 men. But this number tells only part of the story. The vast majority were not volunteers or even conscripts—they were forced laborers. Among them were prisoners of war, concentration camp inmates, and civilians from occupied countries. These men, working under brutal conditions, toiled day and night to carve out the tunnels and construct the factory infrastructure. Many died from overwork, malnutrition, disease, or abuse. The project, like many others in Nazi Germany, was built on human suffering.
Despite the harsh conditions and impossible deadlines, the underground factory took shape. Gigantic tunnels were drilled using explosives and manual labor. Rail systems were laid to move materials and aircraft parts through the mountain. Ingeniously, once completed, finished Me 262 jets would be winched up a long rail track that ran to the top of the mountain, where a short takeoff runway had been carved into the summit. From there, the planes could be flown directly into operation or to nearby airfields.
The REIMAHG facility was never fully operational before the war ended. Though a handful of aircraft were assembled there, the scale of production envisioned by Hitler never materialized. The war ended before the underground jet factory could become a decisive force. When American forces advanced into Thuringia in April 1945, they discovered the site—some of the tunnels still under construction, others already abandoned.
