Fort St. Angelo ( or Fortizza Sant'Anġlu) is a bastioned fort in Birgu, Malta, located at the centre of the Grand Harbour. It was originally built in the medieval period as a castle called the Castrum Maris (; ). It was rebuilt by the Order of Saint John as a bastioned fort called Fort Saint Angelo between the 1530s and the 1560s, and it is best known for its role as the Order's headquarters during the Great Siege of Malta of 1565. A major reconstruction to designs of Carlos de Grunenbergh took place in the 1690s, giving the fort its current appearance. The fort was garrisoned by the British from 1800 to 1979, at times being classified as a stone frigate known as HMS Egmont or later HMS St Angelo. The fort suffered considerable damage during World War II, but it was later restored. In 1998, the upper part of the fort was handed to the Sovereign Military Order of Malta. Fort St. Angelo has been on Malta's tentative list of UNESCO World Heritage Sites since 1998, as part of the Knights' Fortifications around the Harbours of Malta. History Pre-history to antiquity The site was occupied since pre-history and a prominent place of worship in antiquity with the building of the temple of Astarte. The date of its original construction is unknown. However, the prehistoric and classical remains on site, are indicative of a fortified place and a habitable zone. Large ashlar blocks and an Egyptian pink granite column at the top part of the fort still exists inside the chapel. The site was probably later developed by the Arabs 870 AD, but nothing is concrete. Al-Himyarī mentions that the Arabs dismantled a (fortress), but there is no actual reference if this 'fortress' was in Birgu. A rock-cut church close to the area had already existed since Orthodox Christianity in Malta around 600 A.D. and was rebuilt with wood in around 800 A.D. Middle Ages Its probable start as a fortification is the high/late medieval period. In fact, in 1220 Hohenstaufen Emperor Frederick II started to appoint his own Castellani for Malta who needed a place to live and secure the interests of the crown. The remains of a tower that may date back to the 12th century can be traced among the more recent works. The first mention of () is to be found in documents from the 1240s