Horn Head Lookout Post, Coastguard Hill, Horn Head, Co. Donegal

It is a single room with a canted front wall, angled so that whoever stood inside could sweep the horizon in three directions at once. The building is out of use now, its window fittings long gone, its doorway open to the weather, but the shape of it still reads clearly as what it was: a watch post built to catch the first sign of a submarine, a plane, or a stray ship in the Atlantic approaches.

It dates from the early years of the Second World War, when neutral Ireland set up the Coast Watching Service to keep an eye on its coastline. Between 1939 and 1942 the Irish Army built 83 of these lookout posts, spaced five to fifteen miles apart along nearly two thousand miles of coast running from Ballagan Point in County Louth to Inishowen Head in Donegal. Each was built to the same design, assembled from 137 pre-cast concrete blocks, and the sheer scale of getting them all built and staffed made it one of the more demanding engineering efforts the Defence Forces undertook during the war. This one, numbered 77, would have had a rotating crew of between eight and twenty-one men working in pairs on eight or twelve hour shifts, one inside working the telephone, the other outside on patrol, both logging every aircraft and vessel they spotted and passing word back to military intelligence at G2. Inside, a fireplace built into the south wall gave some relief from the exposure of the site; a telephone line, semaphore flags, and a Morse code set were the means of reporting what they saw. At the request of the Allies, the men also painted a large EIRE and the number 77 on the rocks below, a signal to aircrews that this was neutral territory not to be mistaken for a target, and the marking is still visible on the ground at the tip of the headland.

The post did not appear on empty ground. It stands close to the ruined remains of a Napoleonic-era signal tower, and was itself built on the site of an earlier coastguard semaphore station dating to around 1860, so three separate generations of coastal watching have occupied this same stretch of cliff. That layering, Napoleonic tower, Victorian semaphore station, wartime lookout hut, makes the spot a small case study in how a single dramatic vantage point over the Atlantic kept being pressed into strategic use, long after each earlier watch had lapsed. The building itself is plain almost to the point of severity, flat concrete roof, rendered chimneystack, square window openings with nothing left in them, but its position, looking out from the edge of Horn Head toward open water, still explains exactly why it was put there.