Port Island

Half a kilometre from the Cavan shore, Port Island rises from Lough Macnean as a green knot of rock and forgotten stone. Its circular tower still carries a six-and-a-half-metre heart of dressed wall, thick enough to exclude a siege and tall enough to remind a man that exclusion is not the same as understanding. Con O'Rourke may have kept Melaghlin Mac Rannall captive there in 1499, using water and distance as locks; if so, the lake itself became a chamber in the castle. Today the vegetation has taken back the rooms, smoothing the edges of that medieval brutality into ordinary life.