Drimnagh Castle, Long Mile Road, Dublin 12, Co. Dublin

Elsewhere in Ireland, moats that once encircled tower houses and fortified enclosures have long since silted up, been drained for farmland, or vanished under later development. Here, fed by the Bluebell stream and drained through a sluice gate into Lansdowne Valley, the rectangular ring of water continues to do the job it was dug for, keeping the castle grounds set apart from the surrounding ground.

The land at Drimnagh, along with Kimmage and Terenure, passed into the hands of Hugh de Berneval, sometimes recorded as Barnewall, in 1215, and it was he who began fortifying the site. What stands today is younger than that first undertaking; the earliest surviving fabric of the castle dates to the late fourteenth century, with the moat itself built around 1400 as a practical defensive measure, intended to slow any attacking force and to give people and livestock a measure of safety within its enclosure. The castellated walls of the castle and yard were raised in local calp limestone, a dark, fine grained limestone common in the Dublin area, and reinforced with battered buttresses, walls that slope inward as they rise, adding stability at the base. Later additions layered onto this medieval core include an entrance bridge built around 1780 to replace an earlier drawbridge, and a further set of castellated walls put up around 1904, these ones with brick detailing around their openings and pediments, enclosing a coach house to the south. A steel bridge, more utilitarian than either, now carries access across the moat from the school grounds that occupy part of the site today, leading through to the coach house.

The castle underwent an extensive programme of renovation beginning in 1986, which addressed the demesne as a whole, moat, walls, and courtyard included, and repaired the stonework that had suffered over the centuries. A stone platform east of the undercroft, the vaulted storage space typically found at ground level in structures of this kind, gives access down stone steps to the water's edge, one of the few points where the moat can be approached directly rather than viewed from the bridges or the surrounding walls. Between the gardens, stable buildings, and work yard enclosed within the moat, the layout still reads as a working demesne rather than a single isolated tower, the water marking out where that enclosed world once ended and the open countryside began.