The First World War section of the Tower Hill Memorial commemorates almost 12,000 Mercantile Marine casualties who have no grave but the sea. It was unveiled by Queen Mary on 12 December 1928.
The Second World War extension commemorates almost 24,000 casualties. It was unveiled by Queen Elizabeth II on 5 November 1955.
In addition, in 2005, a memorial was built on the site by the Merchant Navy Association (to a design by Gordon Newton) to commemorate the Merchant Navy casualties of the Falklands War.