Auchincruive, 4 miles northeast of Ayr, is part of the ancient seat of the Cathcart's. The present day house (the Robert Adam designed mansion, Oswald Hall) dates from the 1700s, with the estate holding a number of lodges, a tea house and a clock tower. Richard Oswald (a merchant from London, and a commissioner in Paris for peace negotiations with the Americans) bought the estate in 1764.

Following his death in 1784, the estate was run by his widow Mary Ramsay till her death in 1788. Auchincruive then passed to their son Richard Alexander Oswald, a government contractor during the American War.

More recently, Auchincruive was gifted to the Secretary of State by John Hannah of Girvan Mains. It became the home of the Scottish Agricultural College with the Hannah Research Institute being named in his honour.

The estate is also available for use as a venue for outdoor events such as the Ayr Agricultural Show. Oswald Hall can be booked for conferences or musical events. The grounds around the house and along River Ayr can be used by the public for scenic walks.