Kinlough Castle, Tower house in County Mayo, Ireland.

Kinlough Castle is a four-storey tower house on the west bank of the Black River, 3.2 km southwest of Shrule in County Mayo. Its east and west walls have gables but no crenellations, and traces of a bartizan remain in the west wall. The battered base has loops, the entrance a drawbar slot, and three chimney stacks rise above the roofline.

The tower is thought to date from the 13th century. In 1574 Sir John FitzOliver Burke, the MacWilliam Eighter, added two storeys with corner fireplaces. A 1584 map calls it a "McWilliam House". It was mortgaged to the Blakes in 1629, leased to John Darcy in 1668, and Pierce Joyce bought the lands in 1852.

The castle stands as one of Ireland's national monuments, representing architectural developments and construction methods from medieval times through the 16th century.

Kinlough Castle stands on the west bank of the Black River, 3.2 km southwest of Shrule in County Mayo. The tower house is a National Monument and the adjoining Kinlough Church is part of the same monument. The structure is a ruin with no crenellations, so watch your footing around the battered base and the entrance with its drawbar slot.

The ruin is a nesting site for the common swift (Apus apus), a summer migrant that arrives in Ireland to breed and leaves again for Africa. The birds nest in the masonry rather than staying all year, so the tower is occupied by swifts only during the breeding season.