The remains of two temples, one dedicated to the Egyptian god Amun and the other to the Greek goddess Aphrodite, have been discovered in the sunken city of Thonis-Heracleion in the Bay of Aboukir, about 20 miles northeast of Alexandria.

The non-profit European Institute for Underwater Archaeology (IEASM) has been exploring the sunken city since its archaeologists first rediscovered the ruins four miles from the coast in 2000. Surveys of the site uncovered the bed of the former channel of the Canopic Nile, the walls of a temple and the naos of a temple of Amun. This gave archaeologists enough data to identify the city as the Heracleion referred to in the trilingual Ptolemaic-era stele known as the Decree of Canopus. A stele recovered from a shrine to Herakles also used the city’s Egyptian name: Thonis. These finds for the first time established conclusively that the city the Greek residents called Heracleion was called Thonis by the Egyptians.

Founded in the 6th century B.C., Thonis-Heracleion controlled access to the Canopic channel and was the main port of trade between Greece and late Pharaonic Egypt. All ships from Greece were required to stop there. In fact, at its peak it was the biggest port city on the Mediterranean Sea before it was eclipsed by Alexandria. Sixteen shipwrecks dating to between the 6th and 2nd centuries B.C. found at the site attest to the intense trade activity at the site in its heyday. Votive offerings made by merchants and sailors, many of them maritime in motif (miniature anchors, miniature vessels) have been found spread all over the seabed.

The remains of the temple of Amun and sanctuary of Aphrodite were discovered in the city’s south canal. They found massive stone blocks from the temple of Amun which were dislodged in the mid-2nd century B.C. when the temple was destroyed in a cataclysmic flood. Surviving wooden structures under the floor level of the temple have been radiocarbon dated back to the 5th century B.C. Pharaohs came to the Amun temple at Thonis to receive their formal titles and emblems of power. Gold jewelry, silver instruments, alabaster unguentaria and ritual objects including a gold wedjat eye amulet and a lapis lazuli Djed pillar in pristine condition were recovered from the temple treasury.

East of the Amun temple, a Greek sanctuary devoted to Aphrodite was discovered, which yielded imported bronze and ceramic objects. This illustrates that Greeks who were allowed to trade and settle in the city during the time of the Pharaohs of the Saïte dynasty (664 – 525 BC) had their sanctuaries to their own gods. The presence of Greek mercenaries is also seen by numerous finds of Greek weapons. They were defending the access to the Kingdom at the mouth of the Canopic Branch of the Nile. This branch was the largest and the best navigable one in antiquity.

Heracleion never recovered its former importance after the cataclysm of the 2nd century B.C., but it was still inhabited until the late 8th century. A series of earthquakes and rapidly rising sea levels subjected the city to tidal waves that liquified the coastal land. Finally more than 40 square miles of the Nile delta sank under the sea, taking the entire city of Thonis-Heracleion with them.