Black Rock Lighthouse, Black Rock, Co. Mayo

Set on a bare rock outcrop off the Mayo coast, the lighthouse reads less as a utilitarian marker for shipping and more as a piece of considered architecture, its cast iron railings and cavetto-moulded corbels (a concave curve borrowed from classical mouldings) running round the lantern gallery in a band of ironwork that feels deliberately streamlined rather than merely practical.

The tower was designed by George Halpin Junior, who served as Inspector of Works and Lighthouses for the Ballast Board, the body once responsible for Irish harbours and navigation marks, from his appointment in 1854 until his resignation in 1862. Work here was sanctioned in 1857 and begun the following year, but progress was slow enough that the structure was not completed until 1862, and it did not enter service until 1864. The circular tower stands in two stages on a battered plinth of cut granite, its walls tapering upward in the same manner as Halpin's Ballynacourty Point Lighthouse in County Waterford, finished in 1858, suggesting a shared design vocabulary across his output for the Board during this period. Inside, a spiral staircase of cut granite survives, its steps carried on wrought iron balusters supporting a matching handrail, a fitting-out detail that has lasted rather better than the tower's exterior fabric, which was damaged in 1940. The light was automated in 1974, removing the need for resident keepers, and underwent repair as recently as 2011.

Square-headed openings throughout, doors and windows alike, are framed in cut-granite voussoirs, the wedge-shaped stones that once formed a proper arch but here sit flat across a square lintel, a detail that softens what might otherwise be a purely severe exterior. The door itself has been replaced in sheet steel and the window fittings in fixed-pane timber, practical concessions to a structure that continues to stand exposed on its rock, still recognisable as one of the more architecturally considered pieces of maritime infrastructure built along this stretch of coast in the mid nineteenth century.