UNESCO officials say that a British promise to relocate a highway near Stonehenge has gone unfulfilled for 22 years. (Matt Dunham/Associated Press)

UNESCO, the cultural arm of the United Nations, has threatened to put the Tower of London on a list of endangered world heritage sites unless British authorities act immediately to protect seven sites.

Britain has failed to protect several major historical locales including Stonehenge, the neolithic ruins at Skara Brae, Orkney, as well as the old centres of Edinburgh and Bath, United Nations Educational, Scientific and Cultural Organization officials say.

They say the country's government has a legal obligation to safeguard those sites.

They point to planning decisions such as the approval of new office buildings near the Tower of London and the failure to relocate a major highway beside Stonehenge — a promise that has gone unfulfilled for 22 years.

In May, vandals managed to chip off a piece of rock from the ancient circle of stones.

UNESCO is sending two teams of inspectors to Edinburgh and Bath to investigate whether new developments in those cities could damage the "integrity" of their ancient centres.

Edinburgh city council recently passed a motion to approve the building of a hotel, new apartments and offices next to the Royal Mile — the main thoroughfare of the city's Old Town bookended by Holyrood Abbey and Edinburgh Castle.

"It is crucial that [Edinburgh's] outstanding features are preserved and protected," Koichiro Matsuura, the head of UNESCO, told the Scotsman newspaper.

Matsuura's office says it will put the Tower of London on its "world heritage in danger" list next year unless it sees true progress. It's demanding a report by February replying to its concerns.

The U.K.'s Department for Culture, Media and Sport, which has responsibility for protecting the country's 27 world heritage sites, says it is introducing a heritage protection bill which will give all sites in England the same legal protection as a conservation area.