The original artwork will be removed and repainted
For decades the Berlin Wall was the physical symbol of the Cold War "Iron Curtain" between East and West.
But since it was breached in 1989, one remaining part of the wall has taken on a new role, as a 1.3km art gallery.
Age and graffiti have taken their toll on the art, however, and a 2.2m euro project is now under way to restore it.
Organisers say the East Side Gallery is a tribute to those who died, and hope work will be complete by 2009 - the 20th anniversary of the wall's fall.
In January 1989, East German leader Erich Honecker proclaimed that the Berlin Wall, built to prevent people escaping from Soviet-controlled East Berlin to the West, could stand for another 100 years.
But a few months later, the wall was breached by thousands of East Germans, in a powerful sign of the collapse of the Soviet power.
The following year, Berlin invited 118 international artists to decorate the remaining section of the wall with colourful murals, many of them depicting the story behind the structure.
Iconic images, such as an East German Trabant car crashing through the brickwork and a passionate fraternal kiss between Honecker and Soviet leader Leonard Brezhnev, have become a staple of tourist photographs and an important part of Berlin's heritage.
But the curators of the East Side Gallery say the 106 paintings created two decades ago are now barely recognisable.
They say weather, pollution, time and souvenir hunters armed with chisels have left the wall "extremely deteriorated".
"If we don't restore it now it will be too late," said Kani Alavi, of the East Side Gallery Artists' Association.
Some of the iconic images are now almost unrecognisable
Each of the paintings will be removed and then repainted, and the association say it has invited many of the original artists to recreate their images.
In total, about 80% have been contacted and the association has asked for help in finding the rest.
"We have gone to a lot of effort to track down the artists," said Mr Alavi, who was himself responsible for one of the artworks. "It must be authentic."
Where artists have died or cannot be contacted, the organisation will commission others to recreate works, remaining true to the original.
The 2.2m euro ($3m, £1.75m) project began on Wednesday and organisers hope the gallery will be restored to former glory by 9 November next year, two decades after it fell.
Construction of the Berlin Wall began in 1961, in an attempt to stop the flow of millions of people from East to West.
The original barbed wire barrier was gradually replaced with 5m (15ft) concrete panels and the structure eventually extended 165km along the border, 45km of it cutting through Berlin.
About 1,065 people were killed trying to escape from East Germany, scores of them at the Berlin Wall.