Eilean Donan Castle, in the western Highlands of Scotland. It was demolished by three ships of the Royal Navy in 1715, after a two-day bombardment and the taking of the castle. The Navy finished the job using 27 barrels of gunpowder. The reconstruction, which occurred some 200 years later, took a bit longer.
Interesting fact from Wikipedia:
A curious distinction is that it has one of only two left-handed spiral staircases in a castle in Great Britain, as the reigning king at the time of building held a sword with his left hand.
He must have expected that his sons would be left-handed, too.
(Click the image to Gaelicize.)