Tantallon Castle is a mid-14th-century fortress, located 5 kilometres (3.1 mi) east of North Berwick, in East Lothian, Scotland. It sits atop a promontory opposite the Bass Rock, looking out onto the Firth of Forth. The last medieval curtain wall castle to be constructed in Scotland, Tantallon comprises a single wall blocking off the headland, with the other three sides naturally protected by sea cliffs. Tantallon was built in the mid 14th century by William Douglas, 1st Earl of Douglas. It was passed to his illegitimate son, later created Earl of Angus, and despite several sieges, it remained the property of his descendants for much of its history. It was besieged by King James IV in 1491, and again by his successor James V in 1528, 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 of a singular 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 south-west, 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 either end and a heavily fortified gatehouse in the centre, all of which provided residential accommodation.