Vice-Admiral Horatio Lord Nelson's victory and death at the Battle of Trafalgar on the 21st October 1805, is commemorated in this circular naval spy-glass signal tower, designed by Robert Burn, and completed in 1815.
The time-ball drops daily to synchronise with the one o'clock gun firing at the Castle. These are visible and audible signals to ships in Leith Harbour to enable them to set their chronometers as an aid to navigation.
The best panoramic view of Edinburgh is from the top of the tower.
Displays inside the monument explain the history of Calton Hill, the Time-ball and its connection to the nearby Old City Observatory, the Battle of Trafalgar, the Merchant Navy's war effort and the history of the Northern Lighthouse Board.