Not as famous as Eilean Donan but a landmark to anyone sailing out from Oban up the Sound of Mull is Duart Castle on Mull. It has also been a film location including Entrapment (Connery, Catherine Zeta Jones, 1999) and When Eight Bells Toll (Anthony Hopkins, 1971).
What is much less well known about both these iconic Scottish castles is that they're both fakes.
Well not fakes exactly, but they're both 20th century rebuilds of what had previously been ruins.
The original Eilean Donan Castle's end was quite colourful. In 1719, a force of 300 Spanish soldiers landed as part of an ill-conceived Jacobite plot to revive the Stuart dynasty. 46 Spaniards were left to garrison the castle while the remainder marched inland. Two Royal Navy ships bombarded the castle which soon surrendered. It was then blown up. (The remaining Spaniards who had marched inland were, along with some rebel Scots including Eilean Donan's owner, the Earl of Seaforth, and Rob Roy MacGregor (Liam Neeson - 1995), defeated soon after at a battle in nearby Glen Shiel below a peak now called Sgurr nan Spainteach - Gaelic for "Spaniards' Peak".)That's what Eilean Donan Castle looked like for almost 200 years until a 20 year programme of rebuilding began in 1912. The following picture shows the castle in the 1920s when restoration of the tower had been completed but the outbuildings and bridge to the mainland had yet to be tackled. The original Duart Castle's end, by contrast, was less dramatic - it simply crumbled away through disuse from the late 17th century when castles had become redundant as defensive structures and undesirable as residences. This is what Duart looked like before restoration began in 1910 (about the same time as Eilean Donan) Both castles have nice websites - Duart here and Eilean Donan here.
My personal recollections of these castles are, at Eilean Donan in the early 70s, when the Concorde flew overhead on a test flight and it caused all the doors to slam shut: the medieval castle experience was momentarily rudely interrupted by the 20th century supersonic jet experience.
Duart - last day of the opening season, September 1991. Lady Elizabeth MacLean, the dowager chatelaine, showing us round (well coached by her accountants to emphasise that all of the treasures belonged to her son and daughter-in-law for tax reasons) and shoo-ing us into the castle tearoom where there were lots of gateaux needing to be eaten up on the last day of being open to the public. Who cares if the castle's a rebuild!