Castro culture (cultura castrexa, cultura castreja, cultura castriega, cultura castreña, meaning "culture of the hillforts") is the archaeological term for the material culture of the northwestern regions of the Iberian Peninsula (present-day northern Portugal together with the Spanish regions of Galicia, Asturias, and western León) from the end of the Bronze Age (c. 9th century BC) until it was subsumed by Roman culture (c. 1st century BC). It is the culture associated with the Gallaecians and Astures.
The most notable characteristics of this culture are: its walled oppida and hillforts, known locally as castros, from Latin castrum 'castle', and the scarcity of visible burial practices, in spite of the frequent depositions of prestige items and goods, swords and other metallic riches in rocky outcrops, rivers and other aquatic contexts since the Atlantic Bronze Age. This cultural area extended east to the Cares river and south into the lower Douro river valley.
The area of Ave Valley in Portugal, was the core region of this culture, with many small Castro settlements, but also including larger oppida, the cividades (from Latin civitas 'city'), some known as citânias by archaeologists, due to their city-like structure: Cividade de Bagunte (Civitas Bogonti), Cividade de Terroso (Civitas Terroso), Citânia de Briteiros, and Citânia de Sanfins.
The Castro culture emerged during the first two centuries of the first millennium BC, in the region extending from the Douro river up to the Minho, but soon expanding north along the coast, and east following the river valleys, reaching the mountain ranges which separate the Atlantic coast of the Iberian peninsula from the central plateau or meseta. It was the result of the autonomous evolution of Atlantic Bronze Age communities, after the local collapse of the long range Atlantic network of interchange of prestige items.