Elsewhere in the world, according to a report on the world's 100 most endangered sites, the threats include neglect and excessive tourism.

The BBC's Nick Higham:"It's often a race against time"

The World Monuments Fund (WMF) publishes the list to highlight its work to preserve and restore heritage site around the world.

Its range could not be broader, from 9,000-year-old rock art in West Africa to the 1960s National Art Schools in Havana, Cuba.

But it is the damage in the Balkans, ravaged by war since the early 1990s which causes WMF most concern.

Bombed masterpieces

In Croatia the historic city of Vukovar was largely destroyed during the three-month seige by Serbian forces in 1991. When the Serbs finally withdrew in 1997 the city was in ruins.

WMF says sizeable funds and supplies are needed to realise an initial plan to restore important buildings and re-roof all the damaged buildings in the city centre.

The Mostar bridge befoe it finally collapsed

Another Balkan disaster is at Mostar, where the destruction in 1993 of the famous Ottoman bridge, constructed in 1566, put an end to what WMF calls Mostar's long and continuous history of multicultural urban development.

A reconstruction programme has been launched, financed by the World Bank, the Aga Khan Trust, Unesco and the Fund itseld, but additional investors are needed.

Russian troubles

Russia is the conservation black spot and has seven endangered sites on the list. But the picture is balanced by news that parts of St Petersburg's Alexander Palace have been restored and opened to the public for the first time.

WMF points out that since Russia's 1998 financial crisis, conservation projects have slipped way down the list of priorities.

Thousands of tourists flock to Petra every year (Picture courtesy of WMF)

Director Colin Amery acknowledges that because corruption allegations are rife, requests for donations to Russia almost provoke laughter.

But he said that should not put people off. "You can do a lot in Russia really quite cheaply if you can manage it well," he said.

Wealthy offenders

Though problems are of a different order in the UK, WMF points out two sites which have been empty and now suffer from vandalism.

These are EW Pugin's Victorian church of St Francis in Manchester and the 12th Century Abbey Farm near Faversham in Kent. The latter is owned by an Oxford college.

Also at risk in wealthy western Europe is St Pierre Cathedral in Beauvais, France, a masterpiece of Gothic architecture, now dangerously unstable and held up by a temporary tie-and-brace system that increase the structural problems.

Tourist damage

The rock carving is 9,000 years old (Picture courtesy of WMF)

Apart from seismic damage and natural erosion, the developing world's main problem comes from the pressures of tourism, a vital economic resourse for many countries.

The historic 'rose-red' city of Petra in Jordan is under serious threat from tourists, while increasing numbers of visitors to the Pharonic tombs in Egypt's Valley of the Kings inflict "considerable damage" to the tombs' decorated walls.

In Niger, there is the spectacular life-size carving of two giraffes, complete at about 7,000 BC but only fully documented by rock art specialist in 1997.