Tantallon Castle is a ruined mid-14th-century fortress sitting atop a promontory opposite the Bass Rock in Scotland.
The Castle was built in the mid 14th century by William Douglas, the first Earl of Douglas, and remained the property of his descendants for much of its history despite several sieges (by King James IV in 1491, and by his successor James V in 1528).
Tantallon is made of a single wall blocking off the headland, with the other three sides naturally protected by sea cliffs. The curtain wall (over 15 metres/49 ft high, 3.6 metres/12 ft thick, and around 90 metres/300 ft long) is built of the local red sandstone and has a tower at either end and a heavily fortified gatehouse in the center. Alongside the curtain wall is a deep, rock-cut ditch, with a larger second ditch around 100 meters (330 ft) away.
The castle was built before the age of gunpowder artillery, so it had defenses planned for trebuchets, battering rams, and bows and arrows. To defend Tantallon against artillery, later owners filled in-wall chambers to help withstand cannon shot, added gun holes from which to fire at the enemy, and built extra gun defenses outside.
The ruins of Tantallon were sold, in 1699, to Sir Hew Dalrymple, who allowed the castle to decay further and be quarried to a certain extent for stone.