Aigosthena (Αἰγόσθενα) was an ancient Greek fortified port city, 19 km northwest of the ancient city of Megara, to which it belonged. It is situated on the Alkyonides Gulf, a bay of the Gulf of Corinth, infamous for the strong earthquakes it produces (Alkyonides islands). Today, the remains of the ancient city are resting next to a modern town with the same name, known also as Porto Germeno. At Porto Germeno there are taverns and cafe for having your rest and lunch after exploring the archeological site.
The site, surrounded by forested mountains: the Cithaeron to the north and the Pateras to the south, lies 10 km west of Vilia, a town famous mainly for the 1893 church of Transfiguration of Jesus (built by the famous German architect Ernst Ziller). Driving from Athens does not take much longer than an hour (60km).
The ancient site of Aigosthena consisted of a fortified citadel (acropolis) connected to the sea by two fortification walls (forming the lower city).
The fortress was built sometime around the early 4th to the early 3rd century BC, most probably in 343 BC when the Athenians were helping the city-state of Megara to confront the threat of Thiva. For this reason, the fort was manned by a guard of Athenians.
Measuring roughly 90 by 187 m, the citadel was roughly trapezoidal in plan, with the narrower side facing west toward the sea. The citadel was constructed along the contours of a 55 m hill, and was defended by eight artillery towers incorporated into its perimeter wall. There was a primary gate on the west side into the area between the north and south walls to the sea. A small postern (auxiliary) gate was located immediately north of the second tower on the eastern side. Even today, the ancient plan is obvious to the visitor.
The citadel is well maintained and recently (2016) the southeastern tower (SE) has been renovated to its former glory (after it collapsed during the 1981 earthquake in the area). The imposing tower is a square tower, 18m tall with dimensions of each side 9m, that can be seen from far away. It is an excellent example of ancient fortification. The northeastern tower is also under renovation. The Aigosthena castle is in the best condition among the ancient forts that are preserved in Greece.
The access to the citadel is very easy via a new peripheral road that passes parallel the east side of the citadel and the south fortification wall, connecting the coastal road to the road leading to Vilia and Athens. There is an open space under the renovated tower, where one can park his car. There is an informative placard here with useful information of the site. The beauty of the area is enhanced by the olive grove that surrounds the archeological site like a green sea.
The entrance to the citadel is free of charge.
A narrow path starts from the parking lot and ends at a small gate on the west walls. This is the entrance to the citadel. The views from the citadel over the surrounding mountains, the olive groves and the sea are stunning. Besides the renovated tower (which is supposed to be open to the public from Wednesday to Sunday from 9:30 to 16:00), here lies the chapel of Saint George of the Castle (Agios Georgios). In the late post-Byzantine period, the Acropolis hosted a monastery, from which the ruins of cells, as well as the katholikon, the small chapel have survived. The chapel is open to the public, and the visitor can admire its simplicity and the beautiful frescos, still visible.
Of the two long walls used to connect the citadel with the sea and the port, the southern has disappeared. The bed of a river runs along the likely line of the southern wall. The northern wall is pretty well preserved, stretching 370 m to a final tower of which the foundations and fallen blocks are now underwater (only a small part of the wall survives on the beach today). The northern wall consisted of six towers and a fortified gate running in a nearly straight line from the northwest corner of the citadel to the sea.
By that north wall (roughly in the middle of it) stands the small 11th century chapel of Panagia (Virgin Mary). The chapel is built with ancient building material (including inscriptions) at the site of a five-aisled basilica of the 5th c. AD with mosaic floor. The ruins of the basilica are still surrounding the little chapel. There is a fence around the basilica ruins and the chapel, but the door on the north side is open, as well as the door to the chapel itself. The road leading to the fence door is a dirty path starting from the beach road and runs parallel to the walls. A private house stands opposite the fence door.