Legat Owen has been instructed to market Lluesty Hospital in Holywell on behalf of the Betsi Cadwaladr University Health Board.
The 7.4-acre site has views over the Dee Estuary and is allocated for residential use in the planning framework. It also has potential for continuing with a healthcare use.
The land was first developed in 1838 as the Holywell Union Workhouse. In 1948 the site became part of the National Health Service and continued until recently to provide mainly geriatric care.
Stephen Wade, director of Legat Owen, said the site represented an excellent development opportunity. Legat Owen also advised on the sale of former community hospitals in Bangor and Caernarfon.