The fortress of Aigosthena, built on a low hill 450 m. above sea level on the slopes of Mountain Kithairon, commands the eastern end of the Corinthian Culf. The site appears to have been in use from Geometric to Byzantine times. In the Classical period, specifically during the 4th century B.C., when the fortress was constructed, Aigosthena was under Megarian control. The latest research indicates that the fortress was probably built in 343 B.C. with the assistance of the Athenians after they allied themselves with the Megarians to confront the Theban threat. For this reason an Athenian garrison was stationed here.