With a hen under her arm and a smile on her face, the 70-year-old woman appears from behind her bullet-riddled house to unlock the biggest military secret of the Bosnian war.

With help, Sida Kolar lifts a heavy cover, revealing a wooden stairway that disappears into the darkness. A few steps down, it begins - the dank, narrow tunnel that legions revere."Climb down. Look. Hundreds of thousands passed through it," she says. "It saved the city."

Once a lifeline for besieged Sarajevo - used to smuggle in food and weapons and evacuate the seriously wounded - the "Tunnel of Hope" today is quiet and neglected, the only sound the drip of water from the ceiling.

It ends after just a few yards, plugged by a collapsed airport runway and the decay of time.

Those who suffered during the 1992-95 war decided to preserve the tunnel for future generations. Reconstruction has already begun at the other end.

Meanwhile, Sida and her husband are the unofficial proprietors of the treasured passage - a source of inspiration all their own as they endure postwar poverty with little but a cow, a chicken and a ruined house.

When Bosnian Serbs began their siege of Sarajevo in 1992, access to the Bosnian capital was blocked on three sides.

The fourth side, bounded by the airport, was controlled by the United Nations. Under an accord that opened Sarajevo's airport to international relief flights in June 1992, U.N. officials agreed to prevent people from crossing the airport grounds.

Determined to gain a link to the outside world, the Bosnian government army built a tunnel under the runway in 1993. It emerged in the Kolars' yard, about four-tenths of a mile from government-held Sarajevo.

Despite the relatively short distance, the journey through the tunnel could take 45 minutes. It was only 5 feet high because the water table kept engineers from digging any deeper. That forced travelers to walk hunched over, sloshing through ankle-deep mud and water.

With the tunnel wide enough only for one person to pass easily, people scrunched up against the walls while crouched over sideways when traffic was two-way.

Dirty handprints still visible on the walls show it: This was the artery through which the city's life flowed.

Parts of what once were the only cables supplying Sarajevo with power, telephone lines and a fuel pipeline also tell a powerful story.

"This was a 110-kilowatt cable running next to travelers' heads," Sida said. "And they had to walk through water with this next to them. But back then, nobody cared."

Now, city authorities are negotiating with the couple to find them a new home so the tunnel project can be finished.

Until then, the two make their living by showing visitors the tunnel and the museum they've created in their basement.

It's filled with mementos of the city's hardest times - boots, uniforms, shovels, backpacks made of rope, burlap bags bearing the faded letters "Flour, U.S.A."