The present castle was built in the Gothic Revival style. Work on it began in 1743. This castle replaced an earlier 15th-century castle. The foundation stone was laid in October 1746. These dates makes it one of the earliest Gothic Revival buildings, together with Strawberry Hill House. Originally, all the roofs were flat and crenellated. Later, a third floor with pitched roof and dormer windows was added on all four wings and steep conical roofs were added on top of the four round towers. The village of Inveraray was moved in the 1770s to give the castle a more secluded setting. Designers who worked on the house include William Adam and Roger Morris; the interior includes a number of neoclassical rooms created for the 5th Duke by Robert Mylne. These are among the rooms open to the public. James Lees-Milne was not impressed by the house when he visited it in 1943, noting the "ugly" grey stone and calling it "grim and forbidding". In 1975 a devastating fire struck Inveraray and for some time the 12th Duke and his family lived in the castle's basement, while restorations requiring a worldwide fundraising drive were carried out.
Modern era
The castle is open to visitors. Its collection includes more than 1,300 pikes, muskets, swords and other weapons. The 13th Duke and his family live in private apartments occupying two floors and set between two of the four crenellated circular towers. Recent renovations included the installation of the house's first central heating, powered by burning wood-chips from the family's forestry holdings. Inveraray Castle is a Category A listed building. It is surrounded by a garden and an estate of. Besides welcoming visitors to the castle, the estate's activities include commercial forestry, tenanted farming, wind and hydro power, and deer hunting.
The 2012 Christmas episode of Downton Abbey was partly filmed here; the castle portraying the fictional "Duneagle Castle". Inveraray Castle also featured in a series on Scottish castles made by American broadcaster PBS. The "Best of the West" festival, organised by the Duchess, is held at the castle each September.
