Born as a nuragic village, Alghero was occupied in the ancient times before by the Carthaginians and then by the Romans, developing a significant economic activity. The village was an important milestone in the itinerary of the merchants in transit from the main ports of ancient trade, i.e., from the Roman "Nymphaeus" ("Porto Conte") and the thriving “Turris Libyssonis” (the current "Porto Torres").

According to historians the origins of the town date back to the first half of the 11th century, when the Genoese Doria family did strengthen a fishing village along the northwest coast of Sardinia. So was born a port of considerable strategic importance that, for the amount of marine plants deposited currents along the coast, took the name “Aleguerium”, based on the medieval Latin form found in the documents of Doria, (“Salighera” in Sardinian language, and “Alguer” in Catalan). Thanks to its geographical position, Alghero was much scope in businesses which took place in the Mediterranean, therefore the Genoese had defended it against  the  Pisan and Aragonian attacks.

The town remained under Genoese domination until 1353, when the Catalan-Aragonian, strong for the support of the Venetians, defeated Genoese fleet commanded by Admiral Antonio Grimaldi (1300-1358), in a bloody battle ship off to "Porto Conte", occupying the stronghold. In 1354, Peter IV of Aragon (1319-1387) populated Alghero with Catalans, expelling Sardinian and Ligurian.

At the same time the town was annexed by the Crown of Aragon and it stayed for four centuries under the Catalan-Aragonian  and then Spanish domination. Alghero still retains the hallmark feature of the Catalan-Aragonian time, which is manifested in the architecture of its churches,  buildings,  system of fortifications, and  Catalan language. The town in 1720 was acquired by the Savoys.

Today Alghero is a famous tourist harbour, famous for the "Grotte di Nettuno", situated on the promontory of “Capo Caccia”, for its beaches, but also for its historical monuments, like the “Palmavera Nuraghe”  and “Anghelu Ruju” Necropolis.

Etymology

Alghero is a town born in the Middle Ages, and it seems undisputed that the etymology is derived from the Logudorese term "aliga" and the suffix “era,” presumably of Genoese or Pisan origin. The overall significance of the name would be a “town full of seaweeds” (See L. Gambi-G. Corbella, “Città da scoprire: Italia Meridionale e insulare” ["Cities to discover: Southern Italy and the Islands"], 1985: 379). The etymological question was highly controversial, because one spoke of a possible Arabic origin, but then the hypothesis was not considered valid because, as A. Mattone writes,  "[...] 'Alguer' according to some scholars have dated back to Arabic 'al-ghar' ('the cave') (...) but we do not believe that it can be in connection with an Arabic etymology "(See A. Mattone, P. Sanna, “Alghero, La Catalogna, il Mediterraneo: storia di una città e di una minoranza catalana in Italia (XIV-XX secolo” "Alghero, Catalonia, the Mediterranean, history of a city and a Catalan minority in Italy (XIV-XX centuries)", Galizzi, 1994, p. 48).

Anyway, the “Archivio Glottologico Italiano” (Le Monnier, 1886: 267 note) gives for sure that the town's name derives from "aliga" (""seaweed "): [...] About the name of Alghero, it is generally accepted that it derives from 'aliga'; and on the beach of its Gulf algae really are accumulate in large amounts.  There is no need to look  other etymologies, we will only notice that,  in Latin documents, the name of Alghero is written in many ways, such as ‘Allogaria’ or ‘Allagheria’ or even ‘Algaria’; while in Catalans documents the name is written such as ‘Lalguer’ and  ‘Salighera’ in the Sardinian language [...] ".