The complex, which covers an area of 75 acres, was uncovered in the Austrian town of St. Georgen an der Gusen almost 70 years after the end of World War II. The excavations began after researchers found very high radiation levels coming from the area.
The excavation team was led by Austrian filmmaker Andreas Sulzer who told the British newspaper The Sunday Times that the site was "likely the biggest secret weapons production facility of the Third Reich." The facility most likely relied on forced labor from the nearby Mauthausen-Gusen concentration camp and could have been a testing location for a nuclear bomb.
The Mauthausen-Gusen concentration camp forced thousands of prisoners to work tirelessly to build the two complexes and it is believed that 320,000 people died because of the cruel work conditions – 38,000 of them Jews.
The facility is believed to have been headed by the SS General Hans Kammler and is also situated near the B8 Bergkristall factory – the site where the first working jet-powered fighter was created.
The Bergkristall factory was uncovered by the Allied Forces after the war; however the Nazis were able to keep the underground facility made up of tunnels that they built a secret.
The entrance to the facility was only discovered after the excavation team, which includes historians and scientists, discovered information that was gathered by intelligence reports and witnesses testimonies.
The excavation team found SS helmets and other Nazi equipment.
According to a report by the Daily Mail, the excavation team will attempt to remove layers of soil and reinforced concrete along with granite slabs that were used to hide the entrance.
Sulzer says that the prisoners from the concentration camp were from all across Europe and were chosen to work on the giant project because of their specialties in physics, chemistry and other industries.
"We owe it to the victims to finally open the site and reveal the truth," says Sulzer.
The investigation into the nuclear facility began after another investigatory documentary made by Sulzer on Hitler's demands to develop an atomic bomb.
During that investigation, Sulzer discovered a diary belonging to a physicist who was ordered to work for the Nazis. More evidence that helped lead to the discovery of the facility was witness testimony given by scientists who worked on the secret project run by the SS officer Hans Kammler.
Kammler, who approved the plans for the gas chambers and crematorium in Auschwitz, was responsible for Hitler's rocket project. Kammler lived in St. Georgen towards the end of the war.
Sulzer searched archives all around the world for evidence of the SS nuclear weapons project. He learned that on January 2nd 1944, 272 prisoners were taken from Mauthausen to St. Georgen in order to begin the construction of the secret facility.
Up until November 1944, 20,000 out of 40,000 forced laborers were killed during the construction of the tunnels. After the war, Austria spent 20 million dollars in order to cast reinforced concrete tunnels.
However, Sulzer believes that the Austrians missed the secret facility where the atomic bomb project took place. Even though the US took control of the area from the Nazis, the Soviets were responsible for the St. Georgen area until 1955 following the division of Europe and took many of the documents to Moscow.
Experts are trying to find out if there is a relationship between the St. Georgen location to locations in Germany – in which scientists were placed during World War II in order to try and develop the most dangerous weapon of all – the weapon the Americans used for the first and last time in 1945 against Japan - the atomic bomb.
In 2011, nuclear waste was discovered from what is suspected to be a secret facility of the Third Reich – at an old salt mine near the German city of Hanover. More than 126,000 barrels of nuclear materials in a state of decay were found 600 meters below ground.