Immediately behind the Basilica of Santa Luzia lie the excavated remains of one of the best-preserved Iron Age hillforts in northern Portugal. The Citânia de Santa Luzia is a castro-culture settlement whose circular stone foundations are still clearly visible, covering the hilltop in a pattern of streets, houses, and communal spaces that date back over two thousand years.
The site is open and free to wander. The circular stone walls, rarely more than knee-height, give a vivid sense of the scale and density of Iron Age settlement. The inhabitants were the Gallaeci, a Celtic-speaking people who occupied the hillforts of northwest Iberia before and during Roman occupation. Coming up from the basilica, it takes about five minutes to reach the ruins and another twenty to walk the main paths through them.