Built sometime during the 15th or 16th century, this rectangular stone fortress served as both home and defensive stronghold for a local family, likely a branch of the Anglo-Norman lords who had settled in Connacht centuries earlier. The castle’s simple design reflects its practical purpose; thick limestone walls rise four storeys high, punctuated by narrow defensive windows and topped with the remains of stepped battlements.

The interior layout follows the typical pattern of Irish tower houses, with each floor originally connected by a spiral staircase built into the thickness of the wall. The ground floor would have served as storage, whilst the main hall on the first floor provided the principal living space, complete with a large fireplace whose chimney stack can still be traced up the eastern wall. Above this, private chambers occupied the upper floors, offering the lord’s family some comfort and security in an often turbulent countryside. Murder holes above the entrance and narrow loops for arrows or muskets remind visitors that these buildings were designed for defence as much as domesticity.

Today, Castle Lucas stands roofless but largely intact, its walls still imposing against the Mayo landscape. The surrounding earthworks suggest there was once a bawn, or fortified courtyard, where cattle could be protected during raids; a common feature that highlights how these castles functioned as fortified farms rather than purely military structures. Local tradition holds that the castle was abandoned in the 17th century during the Cromwellian conquest, though documentary evidence remains scarce. Its survival offers a tangible link to a time when hundreds of such towers dotted the Irish countryside, each one marking the territory of a family trying to maintain their position in a complex and shifting political landscape.