Tantallon Castle is a ruined medieval fortress atop a promontory opposite the Bass Rock, looking out onto the Firth of Forth. It was built in the mid 14th century by William Douglas and was the last medieval curtain wall castle to be constructed in Scotland.
Despite several sieges, Tantallon remained the property of Douglas descendants for much of its history. It was besieged by King James IV in 1491, and again by his successor James V in 1527, when extensive damage was done. Tantallon saw action in the First Bishops' War in 1639, and again during Oliver Cromwell's invasion of Scotland in 1651, when it was once more severely damaged.
Tantallon is a unique construction within Scotland, the defences comprising only a single large wall securing a coastal promontory. The south-east, north-east, and north-west approaches are naturally defended by steep sea cliffs and were only ever protected by relatively small defensive walls. To the southwest, a massive curtain wall blocks off the end of the promontory, which forms the inner courtyard. The curtain wall is built of the local red sandstone and has a tower at each end and a heavily fortified gatehouse in the centre, all of which provided residential accommodation.
The ruin is today in the care of Historic Environment Scotland and open to the public.
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.