St Michael’s Cave has interested visitors to Gibraltar ever since the days of the Romans. The Cave was long believed to be bottomless. This probably gave birth to the story that the Rock of Gibraltar was linked to the Continent of Africa by a subterranean passage over 15 miles (24km) long under the Strait of Gibraltar. The famous Rock Apes were said to have come to Gibraltar through this under-sea passage. The story also said that the passage emerges at Leonora’s Cave, which begins inside St. Michael’ cave itself
Pomponious Mela, one of the earliest writers on geography who lived about the beginning of the Christian era, described Calpe (the Roman name for Gibraltar) as, ”A mountain with wonderful concavities, which has its western side almost opened by a large cave which may be penetrated far into the interior”. An early description of St. Michael’s Cave says, “it is narrow at its entrance but wide within, like a pitcher”, while a third writer tells us that it was dedicated as a shrine to Hercules.