 In 1638, the Santa Margherita Lines began to be built encircling the land fronts of Birgu and Sengela. Works were suspended in 1645 due to a lack of funds, and they remained unfinished for many years. Following the fall of Candia to the Ottomans in 1669, a second line of fortifications, the Cottonera Lines, began to be built encircling both Birgu and Senglea, as well as the unfinished Santa Margherita Lines. They were begun in 1670, but works stopped in 1680 again due to a lack of funds. By this time, the bastioned enceinte had been built, although other crucial parts had not yet been constructed. Eventually, some effort was done to complete both the Santa Margherita and Cottonera Lines in the early 18th century, although some of the planned ravelins, cavaliers, ditch and other fortifications were never constructed. Fort San Salvatore was built on one of the Cottonera Lines bastions in 1724.
