The Tower of Hercules (Galician and Spanish: Torre de Hércules) is an ancient Roman lighthouse.
The structure is 55 metres (180 ft) tall and overlooks the North Atlantic coast of Spain. The structure, almost 1900 years old and rehabilitated in 1791, is the oldest Roman lighthouse in use today.
The tower is known to have existed by the 2nd century, built or perhaps rebuilt under Trajan, possibly on foundations following a design that was Phoenician in origin. It is thought to be modeled after the Lighthouse of Alexandria. At its base is preserved the cornerstone with the inscription
MARTI AUG.SACR C.SEVIVS LUPUS ARCHTECTUS AEMINIENSIS LVSITANVS.EX.VO
permitting the original lighthouse tower to be ascribed to the architect Gaius Sevius Lupus, from Aeminium (present-day Coimbra, Portugal) in the former province of Lusitania, as an offering dedicated to Mars. The tower has been in constant use since the 2nd century and is considered to be the oldest existing lighthouse in the world.
The earliest known reference to the lighthouse at Brigantium is by Paulus Orosius in Historiae adversum Paganos written around 415-417:
Secundus angulus circium intendit, ubi Brigantia Gallaeciae civitas sita altissimum farum et inter pauca memorandi operis ad speculam Britanniae erigit