Engelberg Tunnel

During World War II it was used as a Nazi forced labor factory for the manufacture and storage of aircraft parts.

In shifts lasting between 12 and 18 hours, Zwangsarbeiter (forced workers) assembled wings for Messerschmitt Me 262 fighter-bombers.

Shortly before the end of World War II all the machinery was removed and the tunnels were blown up.

Lorries slowed significantly before reaching the tunnel causing long back ups of traffic.

Eventually the south exit to the old west tunnel was turned into a memorial to victims of the concentration camp.

The area where the old motorway once stood became green belt land and is popular among walkers and people sledging in winter.

Experts found that the old tunnels were in danger of collapsing so both were entirely filled in using compressed materials in late 2007 to early 2008 at a cost of around €1 million.

The last 20 m (66 ft) of the southern entrance of the west tunnel were left in place as part of the memorial.