A series of concrete road barriers encircled the former US embassy in London post September 11. The embassy is now moving to a more secure location in south London. These barriers were in place for some years and were eventually backed up by a layer of high security fencing.
This defence system, that occupied a London thoroughfare, caused local residents in Mayfair, a very expensive part of London, to take out a one-page ad in the Times newspaper to protest about the fortifications - pleading for its perimeter to widen to include them within it.