Roman engineers built the lighthouse now called the Tower of Hercules outside the port of Brigantium, present-day A Coruña, probably in the late first or early second century CE. A nearby inscription names the architect Gaius Sevius Lupus and dedicates work to Mars Augustus. The tower guided Atlantic shipping along the dangerous northwestern coast of Hispania and advertised Roman control of maritime routes. Its original design likely included a square exterior with an ascending ramp wrapped around a tall internal masonry core.

The Roman core contained stacked chambers beneath the light platform. After imperial administration weakened, the structure’s navigation role became intermittent, and its external ramp and facing were stripped for building stone. Medieval narratives surrounded the surviving tower with stories of Hercules defeating the giant Geryon and founding the city. The monument also served as a landmark, watch point, and symbol in local heraldry. Continuity of recognition helped prevent complete loss even when its original Roman appearance had largely disappeared.

Renewed Atlantic commerce encouraged repairs in the early modern period. A small internal stair was cut through the ancient structure, and the tower again supported maritime signaling. Between 1788 and 1790, naval engineer Eustaquio Giannini carried out the transformation that created its present silhouette. He enclosed the Roman core in a restrained Neoclassical stone casing, added an upper level, installed a new stair, and marked the exterior with a diagonal band recalling the lost ancient ramp. The work restored function without reproducing the original lighthouse exactly.

Later equipment modernized the lantern, optics, and operation, while archaeological investigation clarified Roman foundations and surrounding remains. The lighthouse remains active, making it exceptional among surviving ancient towers, but its beam and service systems are modern. Inside, visitors can see portions of Roman walls and chambers alongside eighteenth-century construction. Conservation has repaired joints, controlled water, and managed coastal weathering. The adjacent sculpture park and excavated features are modern interpretive settings rather than components of one intact Roman precinct.

UNESCO listed the Tower of Hercules in 2009 as the only substantially preserved Roman lighthouse still serving maritime navigation. Its authenticity is layered: the central masonry belongs largely to antiquity, the recognizable exterior is an eighteenth-century restoration, and the signaling apparatus reflects later technology. Present access uses the Giannini stair and is subject to visitor limits and weather. The monument should neither be described as wholly Roman in appearance nor dismissed as a replica; it is an ancient working core protected and reinterpreted by an unusually important historic restoration.