A country house is defined here as a house set in a country estate and serving as a residence for the estate owner. Houses called castles or the equivalent in other languages, but which are not fortified, are included.
The term is used here to refer to the revival of pure Classical architecture starting in late 17th-century France and early 18th-century England and spreading to the rest of Europe, North America and other European colonies, and continuing into the early 20th century. The early phase in England is also known as Palladianism.
Those mansions originally built for the aristocracy and gentry and set now or originally in the countryside. This includes post-medieval castellated mansions.