Túr Martello Ros an Mhíl [Rossaveel Martello Tower], Rossaveel, Co. Galway

Anyone wishing to enter would once have needed a ladder, hauled up or lowered as required, and even the stone channel cut into the base of the opening seems designed for exactly that: a bevelled groove sloping outward and downward, with an iron bar at the top likely once used to fix a rope or ladder in place. It is a small detail, but it tells you plainly that this building was never meant to welcome anyone in a hurry.

The tower dates from around 1804, part of a chain of defensive structures raised along the Irish coast as Britain braced against the possibility of invasion from Napoleonic France. These martello towers, named after a fortified point in Corsica that had impressed British engineers with its resistance to naval bombardment, were built in their dozens around vulnerable stretches of coastline, Rossaveel among them, overlooking what is now known as Cashla or Costelloe Bay. The example here is a freestanding three stage structure, its foundation of roughly coursed rubble stone supporting an ashlar limestone tower, the walls flaring slightly inward as they rise before straightening out in the top five courses. Square headed and camber headed window openings, fitted with iron bars, punctuate the walls, and a small stone causeway once carried a track directly to the base of the tower, allowing access to what would otherwise have been an isolated artillery platform. The quality of the stonework is notable; whoever built it did not skimp on the construction, even for a structure whose sole purpose was military readiness against a threat that, in this case, never materialised on this shore.

What strikes most now is the contrast between the tower's function and its setting. It looks out over the waters of Cashla Bay, a view that in other circumstances might be described in gentler terms, yet the building itself was conceived purely in terms of defence, its high door, thick walls, and barred windows all speaking to a period when the Irish coast was treated as a frontier to be watched and held rather than admired. The tower is now derelict, its ladder long gone, but the architecture still carries the logic of its original purpose: keep the ground floor sealed off, keep the garrison above reach, and keep watch over the bay below.