Heracleion was an ancient Egyptian city near Alexandria. It was known as early as the 12th century BC but its importance grew during the waning days of the pharaohs, the late period. Herakleion was Egypt's main port in the time of the pharaohs. It was famous because it was believed that Helen of Troy and Hercules had visited the city, and that the city had even gained its name from Hercules. There was also a large temple dedicated to the Greek hero at the city center. Pharaoh Nectanebo I made many additions to the temple in the 4th century B.C. In the 6th or 7th century A.D. it sank, probably due to major earthquakes and floods. The ruins submerged in the sea were finally located and rediscovered by the French underwater archaeologist Franck Goddio in 2001.