The harbor was located at the north of the fortress, protected from the north winds. It was an advanced naval base of the Athenians. The Athenian ships often stayed over there waiting for an improvement of the weather before sailing on the Mediterranean Sea. There are ruins of ramps and a marble wall on the southeast side. The area was full of naval facilities and ship sheds. Every ship that entered the harbor had to pay landing taxes. The harbor of Sunyon was one of the principal harbors of the Athenians because of its important strategic position. After the naval battle of Salamis in 480 BC, the Athenians dedicated one of the captured Phoenician ships that was part of the Persian fleet in honor of Poseidon.