The historical evolution of the Tower of Hercules can be followed by means of the inscriptions found throughout the structure itself, as well as through the references made to the tower by classical historians including Ptolemy, Cassius Dio, and Paulus Orosius, who wrote “on the second curve of the peninsula, in the city of Brigantia, a high tower rises, worthy of being mentioned”. It is especially notable that the signature of the lighthouse’s original architect remains visible in a building adjacent to the Tower, dated to the 1st century A.D. It translates as:
"Dedicated to Mars. Caius Sevius Lupus, architect of Aeminium, Lusitania [Coimbra, Portugal], to fulfill a vow".
Much later, in the 17th century the Duke of Uceda left his inscription on a block of stone, which reads:
«Lupus built it to emulate the marvels of Memphis, scaled it using a stairway, and lit up the ships from its peak”,
drawing a comparison between this lighthouse in A Coruña and the one in Alexandria, Egypt »,
During the neoclassical remodeling in the 18th century, José Cornide produced two commemorative plaques located above the entrance doors, which commemorate the work performed during the reigns of Charles III and Charles IV of Spain. During this same century, Eustaquio Giannini left this evidence of his direction of the renovation work:
«DIRIXIO ESTA OBRA EL THENIENTE DE NAVIO INGº ORDINARIO DE MARINA D. EUSTAQUIO GIANNINI».