Fort St. Angelo is a historic fortification located in the Grand Harbour of Valletta, Malta. The fort was originally built in the 13th century as a castle by the Knights of St. John. It was later expanded and fortified by the Order in the 15th century, and was used as their headquarters during the Great Siege of 1565 against the Ottoman Empire.

The fort was extensively modified during the 17th and 18th centuries, with the addition of gun batteries, bastions, and other fortifications. It played a significant role in the defense of Malta during the French blockade of 1798-1800 and the two World Wars.

Today, Fort St. Angelo is open to visitors and houses the National War Museum, which showcases Malta's military history from the Bronze Age to the present day. Visitors can explore the fort's many tunnels, chambers, and galleries, and enjoy panoramic views of the Grand Harbour and Valletta from its ramparts.

Fort St. Angelo has been designated as a UNESCO World Heritage site, along with other fortifications in Malta.