Loudoun Castle is a ruined country house nicknamed the "Windsor of Scotland" located near Galston, in the Loudoun area of Ayrshire, Scotland. The majority of the building was constructed from 1804 to 1811 around existing structures dating to the 15th and 17th centuries. The building was destroyed by fire in 1942 and never rebuilt, while the rest of the property was converted into the Loudoun Castle theme park in 1995, which closed in 2010. The ruins are protected as a category A listed building.