The Sarajevo War Tunnel is a relic from the recent Bosnian War in the 1990s. During the war, the city was put under siege by the Serbian Army and began to suffer from lack of food, water and other resources. During different points in the war, the tunnel was used to transport arms, people, water and even electricity. At some point, a rail cart type system was installed in the tunnel to make transportation easier.
The ceiling of the tunnel is a lot lower than you would expect. At 5’6 I still had to crouch significantly at parts. I can imagine how difficult it must have been to carry supplies through the tunnel for long distances. However, considering the entire system was built in secret by volunteers during a war, its pretty impressive.
During the war the tunnel was over 3000 ft. Today, only a small portion of that still remains. One entrance of the original tunnel, as well as the portion of tunnel is open as a museum in a small neighborhood near Sarajevo. In addition to walking through the tunnel, visitors can also see photos from the war and see a video which depcits the creation of the tunnel as well as documentation of the city residents using the tunnel.
It is possible to visit the tunnel on your own by hiring a cab. Make sure to ask him to wait for you while you visit the museum because the area were the tunnel is located is fairly remote.