Isla is the smallest among the Three Cities in the Cottonera. Built on a tongue of land next to Birgu, it was a logical and natural development in the move to live in the harbour area created by the Knights with their arrival in Malta in 1530. As the population of Birgu grew, it became necessary to build another city on Isola di San Giuliano, as Isla was then known.
In the beginning, the Knights would use Isla for hunting and Grand Master Philip de Villiers l’Isle Adam built a large garden full of olive trees there. Later, Grand Master Juan de Homedes added a small palazzo for recreation. Isla was not only built because of the need of more housing, but also because it was too close to Birgu to remain open to invasion by the enemy.
The attack on the Grand Harbour by the notorious corsair Dragut Reis and his troops in 1551 showed that Isla needed some kind of fortification. The next year the Knights quickly built a strong tower called Fort St Michael, to occupy part of the peninsula. Some years later Grand Master Claude de La Sengle ordered work to start on the building of bastions, so that all of Isla could be transformed into a fortified city. The Italian military engineer Nicolo Bellavanti was in charge of the project.
This new city, which was named Senglea in honour of the Grand Master, was the first city in Malta, before Laparelli’s Valletta, to be planned with a grid pattern of streets and houses. When the Turks besieged the island in 1565, works on Senglea’s bastions were still far from complete.
After the fall of St Elmo, Isla and Birgu were besieged with great vigour by the Turks. Both managed to hold back the Ottoman army for three whole months until a relief force, known as Gran Soccorso, arrived from Sicily, on the day still known among the Maltese as Victory Day. In recognition of the courage shown by this city, the Knights gave it the title of Città Invicta.
After the Great Siege, the Knights rebuilt the bastions, however as happened to Birgu, attention to Isla diminished as the Order moved to the new city. It was only in late 17th century and early 18th century, that the bastions of Isla were strengthened once again.
The engineer Mederico Blondel was responsible for the construction of the new main gate of St Anne which was placed in the most central and important place, following Baroque fortification tradition. The original gate led to the seashore, where today there is the Maċina. Under British rule, Isla saw more changes, especially to its bastions, which unfortunately were torn down by the Admiralty to make way for the construction of the naval shipyard. Three bastions, a ravelin and the ditch were destroyed, while Fort St Michael was demolished in 1921 to make way for a school.