The story of Sketrick Castle
A castle on this spot first appears in the written record in 1470, when the Annals of the Four Masters describe it being taken by a great army led by the O'Neill into Clannaboy to help the MacQuillans. The castle was captured and handed to MacQuillan for safe keeping. The tower house you see today is generally dated to the mid-15th century, built to guard the narrow approach to Sketrick Island and the lough beyond.
It was a substantial building, four storeys high, with ground-floor chambers, a boat bay and a subterranean passage. The largest chamber was covered by a stone vault built over wicker centring, a common medieval technique, and the walls held two ovens. The castle was actively involved in the warfare that ran through this part of Down in the 16th century.
The tower stood largely complete until 1896, when a violent storm demolished about half of it, leaving the sheared, open shell that survives now. In 1957 a small stone-lintelled passage was rediscovered, running eastwards out under the bawn wall to a chamber roofed with a corbelled vault over a freshwater spring, a rare survival that would have given the castle's defenders water during a siege.
Today the tower house and the passage to the spring are State Care Historic Monuments, owned or guarded by the Department for Communities, whose stonemasons and conservation crews maintain the ruin. That is why it stays free and open to walk into, on its island at the edge of Strangford Lough.