The Fortifications of Valetta were built by the Knights of St John, with the star fort of St Elmo being built for the Great Siege of 1565. It fell after a long period of defence, and was the keystone of the subsequent Italian bastion trace fortifications built around the Sciberras Peninsula. Construction of the fortifications was carried out between March 1566 and the 1570s. The plan in the images, by Xwejnusgozo (Own work, CC BY-SA 4.0) shows the layout of the defences as built by the Knights.
The fortifications were continually enhanced during the next three hundred years. This included four counterguards along the land front, which largely remain. Fort St Elmo was also screened with the Carafa Enceinte in the 1680s which included what the British called Abercrombie’s Curtain and Bastion, St Scholastica Curtain, Ball’s Bastion and St Gregory Bastion and Curtain. The Vendome Bastion protected the landward side of Lower Fort St Elmo. The British built extensive coastal batteries on the ramparts on the Carafa Enceinte, and defence electric lights were built into the bastions and curtain walls.