The Defense and National Guard took over the premises after the Nazis left the country in 1945 and in 2000 the OCC took over the keys. Since then work has progressed on a war museum under the school, and local authorities have granted some funding.
During the German occupation the Nazis used the college as a command center for up to 420,000 soldiers. In 1945 command was moved to Lillehammer and commissar Terboven took over the Oslo offices.
In what is now the principal's office, Terboven had a direct phone line to Hitler. In 1941 Russian prisoners built a bunker to protect against bombing. If escape was necessary, there were tunnels.
One underground passage led to a hotel across the street. Another led to Vika, not far away in downtown Oslo, and a third to the SS headquarters. One led all the way to the docks, where Aker Brygge now stands. Another tunnel probably led to a bunker under Ruseløkka School.
"We have tried to find out more about these tunnels but either we run into ignorance or an unwillingness to talk," said Øyvind Skarlund, head of the history department at Oslo Commercial College.
Skarlund said that the tunnels are in disrepair, filled with water, rocks and rats - and the entrance has been walled in.
"But it is a dream to open these tunnels. We don't know if they have been used after the Germans left the country," Skarlund said.
Oslos's city councillor for children and education, Torger Ødegaard, has been fascinated by the story after learning about it.
"In time I hope we can open the bunker and tunnels for a wider public," Ødegaard said.
