Yesterday Congress commemorated the anniversary of the terrorist attacks of 9/11. It is widely believed that the Congress Building itself was a target - but Flight 93 crashed in Pennsylvania before it reached Washington DC.
The Congressional building was successfully attacked in 1814 - by the British. Troops marched on Washington - and burned a number of key buildings including the Capitol and the White House, a fact that is retold to any British visitor when they are taken on a tour. The Library of Congress has a webpage dedicated to the attack - http://memory.loc.gov/ammem/today/aug19.html
