Fort St Elmo guards the tip of the Valletta peninsula, commanding the entrance to both the Grand Harbour and Marsamxett Harbour. Built by the Knights of St John in 1552, it played a central role in the Great Siege of 1565 when the Ottoman fleet of around 40,000 soldiers faced a defending garrison of some 600 knights and 8,000 Maltese soldiers.
The fort now houses the National War Museum, covering Malta's involvement in the Second World War. It also contains a small police museum in the former police barracks. Part of the fort is still in active use as a police academy, which means access to certain areas is restricted, but the main fortifications and museum are open to visitors. On summer evenings the fort hosts the historical re-enactment show In Guardia, with period-costumed knights and gunpowder salutes.