The tower is known to have existed by the 1st century, built or perhaps rebuilt under Trajan, possibly on foundations following a design that was Phoenician in origin. Built with the original plans of the Lighthouse of Alexandria. Its base preserves a cornerstone with the inscription MARTI AUG.SACR C.SEVIVS LVPVS ARCHTECTVS 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 the Roman god of war, Mars. The tower has been in constant use since the 2nd century and is considered to be the oldest extant lighthouse. The original tower was shorter and wider, as the surviving core was surrounded by a spiral ramp. The outline of this ramp is still visible in the restored exterior. The final storey was likely surmounted with a dome.