The Cenotaph in London may be found in Parliament Street and is very close to the Cabinet War Rooms and The Ministry of Defence. (Google Earth co-ordinates 51.502678°, -0.126115°)
It was designed by Sir Edwin Lutyens, and was intended to commemorate the victims of the First World War, but is used to commemorate all of the dead in all wars in which British servicemen have fought. I believe it is based on the Cenotaph in Southampton, and the Cenotaph in Johannesburg and Hong Kong are based on this structure. The dates of the First World War and the Second World War are inscribed on it in Roman numerals.