Tantallon Castle is a single giant wall separating a cliff top promontary - effectively its courtyard - from the main land. Built around 1360, it was the last mediaeval curtain-wall castle constructed in Scotland. The wall protected the castle from the land, and tall sheer cliffs protected it from a seaward approach.

The wall is more than 15 metres (50 feet) high and 90 metres (300 feet) long with a tower at either end and a great gatehouse in the centre, with living accommodation in the towers and gatehouse.

Tantallon was besieged three times: by the forces of James IV in 1491; in 1528 by James V when it was attacked with cannon for three weeks, although little damage was done as the weapons could not be brought close enough to the wall; and in 1651 when Oliver Cromwell and his army invaded Scotland - this time the castle took heavy damage and was abandoned.