Acro-corinth is a huge limestone butte 575 meters high just 2 km south of modern and ancient Corinth. It controls access between the Peloponnese and mainland Greece. Acro-Corinth was used for thousands of years as a natural fortification augmented by its man made walls and battlements all the way up until the mid 1800's. The Germans occupied it in WWII.
From its heights one has an panoramic view and may spy the system of watchtower peaks used in past times to relay messages across the Peloponnese and to Athens. Perhaps even more importantly Acro-corinth has a good water supply collected in cisterns. Acro-corinth is difficult to miss and dominates the surrounding area.
The 7th C BC Sanctuary of Demeter is an ancient temple that lies at the foot of Acro-corinth and is worth visiting. A road climbs from its museum to the Acro-corinth gate and small tourist pavilion.
To enjoy the whole of Acro-corinth approximately three hours is needed to walk the whole area but even an hour or two is enough to appreciate the views which are truly stupendous because on a clear day you can see the Acropolis in Athens and the island of Aegina to the east and far across the Peloponnese where other mountain top bastions reveal themselves. The Gulf of Corinth lies to the north and the Saronic Gulf to the west.
In its glory the fortress walls extended almost 3,000 meters and enclosed 240,000 sq. meters of area. The only path to the top is protected by three lines of fortification contributed to by in times gone by.