Founded by the Doria family in 1102, in an area already previously populated since ancient times, the town soon became strategically important thanks to its geographic position and the sea-bed rich in coral.
At the end of a prolonged siege, culminating in the Battle of Alghero (Porto Conte Bay, 27 August 1353), it was overrun by the Aragonese-Catalans who deported their enemy and repopulated the town with their own colonists. Following complex dynastic events, the citadel then passed to the Spanish Crown, demonstrating such loyalty as to deserve the visit of Emperor Carlos V in 1541. He described the little town as bonita y bien asentada, "charming and well situated", calling the inhabitants todos caballeros, "all noblemen". The Catalan language, culture and traditions still survive today, as do sacred events and famous Easter processions; moreover, the people of Alghero continue to call the town ‘Barcelloneta’, ‘little Barcelona’.