The castle was built as a residence in 1808 by the architect Robert Lugar at the order of John Buchanan of Ardoch, a partner in the Glasgow Ship Bank. This listed building is an early example of the Scottish baronial style popular in the 19th and early 20th centuries. The building's turrets and lancet windows are purely decorative.
The new castle used stone from an earlier castle built near the current site by the Earl of Lennox in 1238 and occupied by the Lennox family until approximately 1390. Situated nearer the water than the present day castle, the earlier structure was abandoned in favour of stronghold on the island of Inchmurrin that was considered to be more secure against both the spread of disease and attack by hostile forces.
All that remains of the original structure is a mound that once formed the moat. This site is given statutory protection under the Ancient Monuments and Archaeological Areas Act 1979.
The current castle grounds feature a walled garden with trees and shrubs, including the rhododendrons and azaleas that reach full bloom in late May and early June.
The Countryside Ranger Service is based at the current castle. The ground floor has a visitors centre with facilities including a gift shop, car park, toilets, and tea room.