Archaeologists excavating on Ons Island in north-western Spain have discovered a possible Iron Age wall beneath a Roman-period building, challenging previous interpretations of how the island’s ancient settlement developed.
The discovery was made at Castelo dos Mouros, a fortified settlement in Pontevedra, Galicia, where archaeological investigations have been conducted since 2021.
Researchers from the Xunta de Galicia and the University of Vigo’s Group for the Study of Archaeology, Antiquity and Territory (GEAAT) uncovered the wall in an area where only Roman remains had previously been identified.
Earlier excavations east of the fortified enclosure revealed evidence that the settlement expanded beyond its defences during the Roman period.
The latest campaign has confirmed the presence of a Roman building in this area. However, beneath the occupation layers of one of its rooms, archaeologists encountered an earlier wall that appears to belong to the Iron Age hillfort.
Iron Age occupation outside the walls
The discovery could alter current interpretations of the settlement’s development.
Until now, archaeological evidence suggested that the Iron Age population was largely concentrated within the fortified enclosure, while expansion onto the lower terraces occurred during the Roman period.
Finding a potentially pre-Roman structure outside the fortifications suggests that Iron Age occupation may have been more extensive than previously thought.
Further excavation will be required to determine the date and function of the wall, as well as its relationship with the wider settlement.
Five Iron Age dwellings identified
Archaeologists have also continued investigating the intermediate terrace of Castelo dos Mouros, where several Iron Age structures have previously been discovered.
Excavation of a dwelling first identified in 2025 has continued, while work has been completed on the largest structure found on the terrace.
Inside the dwelling, archaeologists identified a possible central hearth and another feature formed from vertically positioned stone slabs, the function of which remains under investigation.
A newly discovered curved wall has also brought the number of identified dwellings on the terrace to five, indicating that this part of the hillfort was intensively occupied during the Iron Age.
Nine centuries of occupation
Successive campaigns since 2021 indicate that Castelo dos Mouros was occupied for approximately nine centuries.
Previous investigations suggested that the earlier Castro culture was primarily concentrated within the fortified area, while occupation expanded downslope towards Canexol beach during the Roman period.
Archaeologists have also discovered remains associated with Roman fish-salting installations near the beach, providing evidence for the exploitation and processing of marine resources.
The latest discoveries suggest that the transition between Iron Age and Roman occupation may have been more complex, with settlement outside the fortifications potentially beginning earlier than previously recognised.
The campaign is concluding with conservation work to protect the newly exposed structures ahead of future excavations and the planned presentation of the archaeological site to the public.
Sources : Lareson
