Just across from the Houses of Parliament in the Old Palace Yard is the Golden Jubilee Sundial. This was a gift from Parliament to the Queen to celebrate her Golden Jubilee. It is an analemmatic sundial which means it is horizontal and has a vertical gnomon (the part of the sundial that casts a shadow) – in this case the head of the person standing on the appropriate dateline.
Old Palace Yard itself is interesting as it was the site of executions, most notably that of Sir Walter Raleigh and Guy Fawkes along with others involved in the Gunpowder Plot.
Louise Jayne's Blog 