Dursey Watch Tower, Tilickafinna, Dursey Island, Co. Cork

What catches the eye first are the bartizans, small overhanging turrets supported on courses of corbelled stone, projecting from the corners like afterthoughts that were in fact the whole point: they allowed defenders to look, and if necessary fire, straight down the walls at anyone attempting to storm the base. Few of these features survive so cleanly on Ireland's signal towers, and here they remain finely worked enough to read clearly as functioning defensive elements rather than mere decoration.

The tower dates to around 1805, part of a chain of signal towers thrown up along the Irish coast in response to the perceived threat of a French invasion during the Napoleonic Wars. Dursey, jutting into the Atlantic at the mouth of Bantry Bay, a stretch of coastline already associated with French naval ambitions after the failed 1796 expedition, was an obvious point to watch. The structure is a freestanding, two-bay, three-stage building of rendered and rubble stone, its walls once hung with slate against the weather, capped with a parapet that, together with the bartizans, gives the whole tower its fortified, almost castellated silhouette. A later extension was added to the north-east elevation at some point after construction, softening the original footprint without disguising it. Square-headed window openings, each fitted with sills, lintels and voussoirs (the wedge-shaped stones that form an arch or lintel and carry the load above an opening), puncture the walls in a plain, functional rhythm, while the main door, set at first-floor level on the south-west side for obvious defensive reasons, follows the same pattern of sill, lintel and voussoirs.

Long disused, the tower now functions mainly as a landmark on an island already known for its dramatic isolation, reached only by Ireland's sole cable car crossing. Its survival, corner turrets and all, makes it a rare chance to see how these coastal watch-posts were built to be lived in as well as fought from, three stages of habitable space wrapped around a single defensive purpose that, in the end, was never tested.