Built on a 12th century motte, Myrton Castle is a ruined 16th century L-plan tower house. It rose to four storeys and a garret, within a parapet, and had open rounds at the corner. There was another building at the base of the motte.
It was originally a property of the MacCullochs. Sir Alexander MacCulloch of Myrton torched Dunskey Castle in 1503, and was the King's Master Falconer. James 1V visited in 1504 (and 1511) during a pilgrimage to the shrine of St. Ninian at Whithorn. The tower was ruined by the late 17th century, and a new house was built nearby. The property was sold to the Maxwells of Monreith. In 1685, who removed to Myrton from nearby Dowies. They altered the building, and a wing was still occupied in the 19th century. The Maxwells built Monreith House close by, which is still occupied.