Ballygannon House and Estate
About one mile (1.6km) to the south of Greystones the enormous ruins are visible among trees on the saltmarsh. The ruins are on private land, but support a tremendous amount of wildlife, including birds of prey.
Ballygannon belonged the the O'Byrne clan, and was built in 1605. It was inhabited until the 1930s by the Scotts. Sea captain, Hopton Scott, came to the house in 1689, during the Williamite War. His ship ran aground on a sandbank off Kilcoole and he was given shelter by Thaddeus O'Byrne. He married O'Byrne's eldest daughter, Randelia, and inherited the house on Thaddeus's death.