During the siege Sarajevo was connected to the territories controlled by the Bosnian Army only through the tunnel that run under the airport, which was a free UN zone, connecting the neighourhood of Dobrinja and the village of Butmir. The tunnel was dug in six months during 1993 and it allowed to people to go in and out of the city, and to bring food, humanitarian aid, weapons and ammunitions, and fuel to the defenders.
Probably, the tunnel saved Sarajevo.
Today, a museum is hosted in the house where the tunnel started from in Butmir, and only 20 metres of it remains.

See a video made with the Kolarev family who owns the house-museum.

Read an article from the BBC website.