Northburgh Castle (Greencastle, Inishowen)

Completed in 1305 by Richard Óg de Burgh, 2nd Earl of Ulster, Northburgh Castle (known locally as Greencastle) stands on the Inishowen peninsula as a masterpiece of late medieval military architecture. Built to command Lough Foyle and project Norman power over the strategic peninsula, the castle's oval enclosure features a distinctive twin-towered polygonal gatehouse—a design that drew inspiration from Edward I's ambitious Welsh castles at Harlech and Caernarfon. The engineering challenges posed by its rocky foundation necessitated an innovative design, and the resulting fortress became renowned as one of the largest and most impressive Anglo-Norman buildings of its kind in Ireland, as noted in the Ulster Journal of Archaeology.

Northburgh's history reflects the volatile politics of the medieval north. In 1316, Robert the Bruce's brother Edward Bruce captured the castle and held it until his death in 1318. A darker chapter unfolded when Walter Liath de Burgh died of starvation while imprisoned there in 1331–1332, a grim testament to the brutal nature of medieval conflict. Following William Donn de Burgh's death, the O'Doherty family became its stronghold, and the castle passed through generations of local lords.

Today, Northburgh remains under the management of the Government of Ireland's Office of Public Works and is freely accessible to visitors via two routes—from the town itself or along the shoreline of Lough Foyle. The surviving twin-towered gatehouse and later polygonal tower provide tangible evidence of medieval ambition and engineering skill. A local conservation group formed in 2021 continues efforts to preserve this remarkable structure for future generations, ensuring that one of Ulster's finest Norman fortresses remains visible to those who seek it out.