Blacksod Point Lighthouse, Fallmore, Co. Mayo

But it is precisely this graduated stacking of openings, each floor's windows a little smaller than the one below, that gives Blacksod Point Lighthouse its distinctive tiered silhouette, along with a hint of Tudor Revival styling in the window surrounds that would not look out of place on a manor house. The battered tower, meaning its walls taper gently inward as they rise for stability, sits at the centre of a symmetrical footprint flanked by lower recessed end bays, the whole composition considered an important survival of mid-nineteenth-century engineering in County Mayo.

The lighthouse was designed in 1863 by John Swan Sloane, who served as Superintendent of Foremen and Works for the Ballast Board, the body then responsible for Irish harbours and lights, from 1862 until 1877. Construction ran from 1864 to 1865, with the light commissioned in 1866. The granite used throughout, giving the tower its warm reddish hue, came from the Altmore Quarries, owned at the time by the Reverend Sir William Palmer. The building was electrified in 1967, but its fabric, both outside and in, has survived largely intact, down to the timber sash windows and cast-iron rainwater fittings. Its most consequential moment, however, came not from architecture but from meteorology: on 4th June 1944, Ted Sweeney, who ran the weather station here, radioed in a forecast that proved decisive in the Allied decision to launch the D-Day landings two days later, on 6th June 1944.

Set perpendicular to the road on a granite-flagged platform, the lighthouse still shows the practical thinking behind its 1860s design, from the double-pile slate roofs with their distinctive M-profile to the timber shutters protecting the end-bay windows against Atlantic weather. The setting, exposed and often windswept, is very much part of what the building was built to withstand, and it remains easy to see why a forecast issued from this particular spot on the edge of Mayo carried the weight it did in the summer of 1944.