The Old Venetian Fortress of Corfu covers the promontory which initially contained the old town of Corfu that had emerged during Byzantine times.
Before the Venetian era the promontory, which lies between the Gulf of Kerkyra to the north and Garitsa Bay to the south, was defended by Byzantine fortifications which the Venetians largely replaced with fortifications of their own design. As part of their defensive plans the Venetians separated the promontory from the rest of the city of Corfu by creating the Contrafossa, a moat which is a sea channel connecting the Gulf of Kerkyra to the North with the Bay of Garitsa to the South, converting the citadel into an artificial island.
The fort successfully repulsed all three major Ottoman sieges: the great siege of 1537, the siege of 1571 and the second great siege of Corfu in 1716.
In 1718 lightning struck the powder magazine at Castel da Mare causing an explosion which created a chain reaction during which three secondary ammunition facilities also exploded, this in turn destroying most buildings inside the castle including the palace of the Captain General of the fortress, and many city buildings. Commander of the fortress and hundreds of others died in the explosion.
The fortress houses today the Public library of Corfu which is located in the old British barracks. The fortress grounds are also used for various types of art and culture exhibits. The Hellenic Music Research Lab of the Ionian University is also located at the Old Fortress.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.