During the siege, thousands of Sarajevans relied on the Red Cross

The tunnel was dug by volunteers working in eight-hour shifts.

All the digging was done with a pick and shovel - the detritus was taken away in wheelbarrows.

Work began in January 1993 and finished six months later. On 30 July 1993, two men digging from each end joined hands under the runway of Sarajevo airport.

Only 20 metres of the tunnel survive - the rest has collapsed. To get into the existing section, you have to go down into the basement of a house belonging to the Kolar family.

Difficult journeys

Edis Kolar went through the tunnel more times than he can remember - but what he does recall are many long, difficult and dangerous journeys through its confines.

Without this tunnel Sarajevo couldn't stay as a free town

Edis Kolar

"When you are walking through the hole, you would sometimes walk for more than two hours," he said.

"Inside we had steel supports, and many people hit their heads . . . you can't have good memories."

The airport was supposed to be a neutral zone, controlled by the UN. But often, it was closed - either because of the weather or because of shelling from the besieging Serb forces.

Anything brought in through the airport was also open to inspection. The tunnel was a way of bypassing the arms embargo on Bosnia, bringing in weapons for government army within the city.

Without the tunnel, Edis Kolar says the city would have fallen.

"Sarajevo couldn't stay as a free town . . . that is only way how soldiers could get weapons, and as you know, without munitions, weapons, you can't organise defence."

Proud moment

Part of the Kolar house are now a museum. The basement holds army uniforms, shell casings, and empty sacks of humanitarian aid.

Former President Izetbegovic used the tunnel in 1993

There is also a wheelchair, for those who were too frail to walk through the tunnel unaided.

When the former Bosnian president Alija Izetbegovic used the tunnel, he had his own wheelchair.

Edis Kolar, who was 18 at the time, pushed his president for the whole 800 metres - the proudest day of his life, he says.

During the war, the suffering of Sarajevo's people was one of the few propaganda weapons available to the Muslim side - so Mr Izetbegovic's government restricted the number of people who could use the tunnel to leave.

There's no doubt that war profiteers also did very well out of the goods smuggled in.

But without the tunnel, the citizens of Sarajevo would have suffered even more - and the siege defences might well have failed.