London ? The U.N.’s cultural body said it has its eye on the tower William the Conqueror built in the 11th Century.

According to a UNESCO interim report, the Tower of London, one of Britain’s top tourist attractions, will be added to the list of endangered world heritage sites unless the threat from encroaching skyscrapers is resolved.

Local planners had not done enough to ensure that views of and from the fortress would not be obstructed by surrounding development, including a 1,016-foot building known as the “Shard of Glass” that would be Britain’s tallest when completed in 2010, the report said.

“It’s a question of visual integrity – and that’s a problem in all major cities,” World Heritage Center spokeswoman Gina Doubleday said.

Although being listed as an endangered heritage site can help secure additional funding and support, citing the Tower would be an embarrassment for Britain. The only site in the developed world currently listed as endangered is Everglades National Park in Florida, which made the list in 1993.