Castro Culture and the Architecture of the Hillforts

The Castro culture designates the body of material traditions and ways of dwelling that, during the Iron Age, marked the northwestern Iberian Peninsula — roughly the territory between the rivers Douro and Minho, extending across Galicia and into part of Asturias and western León. Its name derives from the type of settlement that defines it: the castro, a fortified cluster set on high, defensible sites that commanded the valley and the cultivated fields. Formed from an Atlantic substratum of the late Bronze Age, with its first manifestations already in the ninth century BC, the Castro culture reached its apogee between the third century BC and the first century AD, continuing into the so-called Galaeco-Roman phase, when it came into contact with — and ultimately dissolved into — the world of Rome.

The hillforts: siting and defence

The castro is, above all, a response to the territory and to insecurity. People chose spurs, knolls and steep-sided hilltops, reinforced by one or more lines of rampart — frequently three, sometimes four — which enclosed the settlement concentrically. The ramparts, of drystone with parallel facings and a fill of earth and blocks, were combined with ditches and, in certain cases, with fields of set stones (chevaux de frise) that hindered any assault. The density of these sites is remarkable: the Alto Minho ranks among the most densely “castro-bearing” areas in the whole Peninsula. Although most corresponded to communities of a few dozen or a few hundred people, the largest settlements evolved into true proto-urban agglomerations, the citânias, with ordered streets, water-drainage systems and cisterns — signs of a planning that anticipates the city.

The circular house and domestic space

The most recognisable element of Castro architecture is the circular house. Raised in drystone — granite in granitic areas, schist in the east — it had a conical thatched roof supported by a central post and generally measured between three and ten metres in diameter. In the early phases these dwellings were scattered in an apparently disordered way; over time, especially in the final phase, they came to be organised into enclosed courtyards bringing together several units — dwelling, storeroom, kitchen — around a common space, a sign of an extended family and of growing social complexity. The traditional reading of an egalitarian society has been qualified: the difference in size between houses and the unequal access to prestige goods suggest the formation of privileged groups.

The shift from thatch and timber to stone accompanies the spread of iron tools: it was the new metal that made it possible to work granite and to fix in durable construction what had previously been perishable.

The most eloquent examples of this architecture are preserved at sites such as the Citânia de Briteiros, in Guimarães, and the Citânia de Sanfins, in Paços de Ferreira, where one can see streets, reconstructed houses and the characteristic Castro baths — spaces for bathing and steam whose inner chamber was separated by a monumental slab, the pedra formosa, ornamented with geometric motifs. Further south, the Castro de Monte Mozinho, in Penafiel, shows the late expansion of these settlements and their continuity well into the Roman period.

Art, symbols and the end of a world

Castro creativity found expression above all in goldwork — torcs, earrings and gold bracelets of extraordinary quality — and in a decoration of abstract taste, with rosettes, triskeles, spirals, swastikas and plaitwork running across stone, ceramics and metal. Among the statuary, the Galaecian warriors stand out: stone figures of armed men with round shield and dagger, an expression of a military elite and of the group’s memory. Set within the broader frame of the Iron Age of the northwest, the Castro culture did not disappear abruptly: the Roman conquest destroyed and depopulated many hillforts, but integrated and transformed others, which became Romanised while keeping traits of their own. Today these settlements constitute an essential chapter of the great periods and styles of architecture in Portugal, testimony to a civilisation of stone predating the classical city.