Castle at Kilmartin, Scotland, which was the seat of the Kings of Dalriada, arguably the first kings of Scotland.

The castle is so old (700AD or so?) that it is little more than a few ruins of walls (3 feet high) at the top of a big (200 foot high?) rock that looks out over a bay and the surrounding fields. Well worth a visit to the kilmartin area and a walk up to the castle.