Ons Island is much more than a sun-and-beach destination. The only inhabited island in the Maritime-Terrestrial National Park of the Atlantic Islands of Galicia, this enclave located at the entrance to the Pontevedra estuary brings together a natural, historical and cultural heritage that makes it a true open-air museum, with remains spanning from the Iron Age to the 20th century.
In addition to hosting some of the most valuable ecosystems on the Galician coast, Ons preserves an extraordinary archaeological wealth. Among its great treasures stands out the Castelo dos Mouros archaeological site, where the Group for Studies in Archaeology, Antiquity and Territory (GEAAT), of the University of Vigo, has been carrying out excavation campaigns for several years. The works have made it possible to document the oldest known permanent human settlement on the island, a settlement founded around the 4th century BC and inhabited until the 5th century AD.
The investigations have brought to light the remains of a defensive wall, still visible from the sea, and several dwellings that show the transition between the Castro culture and Romanization. Among the most unusual finds is a small set of bronze coins hidden in a Roman dwelling, as well as evidence of a fire that caused the building to collapse in the final years of the Roman Empire.
Very nearby, at Canexol beach, traces of the intense Roman economic activity appear. Two fish-salting factories have been located there, and there are indications of a third. A purple-dye production factory was also discovered, a valuable dye obtained from Stramonita haemastoma (murex), a marine mollusc now disappeared from the Rías Baixas. This find makes Ons the northernmost enclave of the former Roman Empire where the commercial production of this prized dye has been documented.
The journey through history continues in the medieval period with the enigmatic Laxe do Crego, a tomb carved into the rock beside the sea whose original cover is now preserved at the Curro interpretation centre, where pieces from the archaeological excavations carried out on the island are also exhibited.
After centuries of depopulation, marked by the insecurity of the coast and incursions by pirates and privateers, Ons once again had a stable population at the beginning of the 19th century. Administratively integrated into the municipality of Bueu, the island gradually formed a community with its own identity, with a church, cemetery, homes and a way of life linked to the sea and agriculture.
Precisely in 2026, the centenary of the main renovation and extension of the Ons Lighthouse is commemorated, one of the most recognisable symbols of the island and of the entrance to the Pontevedra estuary. Coinciding with this anniversary, its partial conversion into a museum is being studied in order to highlight its history and its role in navigation. An anniversary that reinforces the idea of Ons as a true cultural beacon: a place where nature, heritage, archaeology and collective memory illuminate centuries of the history of Galicia.
