Cottonera is a group of three adjacent cities in Malta with a population of about 11,000 (2014): Cospicua (aka Bormla), Vittoriosa (aka Birgu) and Senglea (aka L'Isla). They are collectively also known as the Three Cities.
Vittoriosa used to be (and still is by the Maltese) called Birgu (Borgo) and, having been a Phoenician/Carthaginian settlement as well as a Greek trading post, is probably older than Mdina. It served throughout Malta's history as its main port town with the fort at the entrance to the bay it protects often being considered more important than, and having rulers different from the rest of the island. When the at the time maritime Knights of St. John were given control of Malta by the Pope and the Holy Roman emperor they, to the relief of the old aristocracy of mixed Catalan, Aragonese, Swabian and Angevin Anjou descent, didn't choose landlocked Mdina as its base but naval Birgu instead. They promptly set out to strengthen the ancient defenses and build an 'Auberge' for each of the different 'Langues' (a Langue is a group of knights sharing a common language, an Auberge a residence for each Langue).
The Turkish Sultan Suleiman the Magnificent decided to try and take Malta in 1565 and sent an armada with 30–40,000 men under the leadership of admiral Turgut_Reis (Torgut Reis, Dragut, Draghouth) with the home of the knights, Birgu and Senglea, as main objective. The siege of Birgu and Senglea lasted several months and culminated in a dramatic episode when the Turks finally breached the defenses. Grand Master of the Knights, Jean de la Vallette, then decided to blow up the bridge linking the town to Fort St. Angelo at the end of the peninsula, so that none of the knights would be able to withdraw and would have to die making a last stand on the central square side by side with the locals of Birgu who had fought with them. Just as the Turks were pouring into the town down the short road to the square a group of Maltese who had ridden down from Mdina set to torching the virtually unguarded Turkish camp giving them the impression that they were being attacked from the rear. The Turks retreated in disarray mere yards from their objective, a victory which would have changed the course of Mediterranean history.
In recognition of this event the name Vittoriosa meaning victory was given to the town. The Knights were hailed in Europe as saviors of the west and acquired huge funds with which they set forth to build Valletta, thus ending Birgu's short spell as capital of Malta.
The area of the Grand Harbour became very important during the 19th century for Malta as it became a stop-over for any British ships between Gibraltar and the Suez canal. In this area, in particular further south around Senglea became the industrial centre of the country with many docks for shipbuilding being constructed. Sadly this made it a main target for an extremely harsh bombing campaign during World War II. The area around the Grand Harbour counts as one of the most intensely bombed in the world which caused incalculable damage to this historic area. As the main industry has moved away from the area, and the tourist areas are concentrated in Sliema and further north the Cottonera is mercifully spared from the unchecked tourist development which has scarred other parts of the country, this area is surprisingly devoid of any tourism. Part of fort St Angelo has been returned to the Sovereign Military and Hospitaller Order of St. John of Jerusalem of Rhodes and of Malta (one of the orders which trace their origin to the original Hospitaller order of Knights of St John) and is being conserved and restored.
Tourist activity has increased in Birgu, as restaurants and a marina for magnificent yachts have opened (and some new flats of questionable taste being built near Fort St Angelo).
The Three Cities are on the opposite side of the Grand Harbour to Valletta, one can see the peninsulas beautifully from anywhere on the south side of the capital facing the water. They can be easily reached by bus from Valletta, the ride takes about 15 minutes.
The Three Cities is made up of two adjacent peninsulas each about a kilometer in length: Vittoriosa and Senglea, and the area which joins the two; Cospicua.
A car is the best option for getting around as public transport doesn't actually go anywhere onto the peninsulas. If you're visiting just Vittoriosa or Senglea then just parking somewhere at the beginning of the peninsulas rather than trying to navigate the maze-like streets is the best option.
The entire area was devastated by Nazi bombers during World War II, and so much of the towns are rebuilt. The place with the most interesting remaining buildings is Vittoriosa, although the tip of Senglea is worth visiting for the view. Birgu has a history going back to pre-Roman times, whereas the other two are more recent. Senglea was founded by Grand Master Claude de la Sengle a few years prior to the Great Siege, and the Bormla mosts dates from after the Great Siege of 1565.