Killymoon Castle stands about 2 kilometres south of Cookstown on the north bank of the Ballinderry River, a Gothic Revival country house built in 1803 to a design by John Nash. The castle is a striking building — Nash's characteristic battlements and towers in local limestone beside the river — and the estate grounds, now managed as a golf club, are accessible to visitors who want to view the exterior.
The castle itself is privately owned and not open for interior visits, but the exterior and the surrounding grounds are one of the better-preserved examples of early 19th-century Picturesque Gothic design in Northern Ireland. The combination of Nash's architecture, the mature trees of the estate, and the riverside setting makes a good short excursion from the town centre. The Ballinderry River here is a good salmon river, and fishing rights on parts of the stretch can be booked through local agencies.