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 Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.