O'Brien's Castle

Historic Building in Inisheer

Built in the 14th century on the island's highest point, this tower house was constructed within the remains of a ring fort called Dún Formna, dating from as early as the 1st century AD. The 100m climb rewards with a sweeping panorama across clover-covered fields to the beach and harbour. The views are especially dramatic at sunset. You're free to walk around the ruins.