Inishturk Signal Tower, Inishturk, Co. Mayo

There is no roof, no floor, no glass in the openings; only the stone shell of a square tower, two stages tall, standing alone in ground that has long since gone to grass and scrub. Its isolation is the point. Signal towers were built to watch empty horizons, and this one still does, in a fashion, even in ruin.

The tower dates from 1805-6, part of a wave of coastal defence construction prompted by fears of French invasion during the Napoleonic Wars. Britain and Ireland were rimmed with such towers in this period, each built to a broadly similar single-bay, two-stage design, sited on elevated ground with clear sightlines to the next station along the coast. Signals, originally flags and later semaphore arms, could be passed rapidly from tower to tower, giving early warning of enemy ships long before a message could travel by road. Inishturk's tower belongs to a small group of related early nineteenth-century structures on the island, and it represents one of the more legible survivals of that network's built fabric on this stretch of the Mayo coast, even though it now stands as a shell rather than a functioning structure.

What remains today is modest: four walls of a square-plan tower, unroofed, set within grounds that have not been maintained as a managed site. There is no visitor infrastructure to speak of, and the appeal lies largely in the setting itself, an elevated position chosen two centuries ago for its long views out over the Atlantic approaches, still commanding the same stretch of sea and sky.