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Photo: Dumphasizer, CC BY-SA 2.0 via Wikimedia Commons
A well-preserved 15th-century tower house on the lake shore. The owners were ousted after the Glorious Revolution of 1688 and it became a barracks until the 19th century, so it was kept repaired. Visit by guided tour.
Ross Castle is a 15th-century tower house and keep on the edge of Lough Leane, in Killarney National Park, County Kerry, Ireland. It is the ancestral home of the Chiefs of the Clan O'Donoghue, later associated with the Brownes of Killarney.
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This now hosts the park visitor centre. It was originally a grand 18th-century chateau but proved serially combustible, so eventually the owners gave up and decamped to the stables, converting them into the present house.
The first monastery was founded in the 6th century, but the ruins you see now are of the Franciscan friary of 1448. (Actually not an abbey, where monks live in seclusion: friars preached in their locality.) It was smashed up on several occasions before Dissolution and a final scourging by Cromwell. The ruin is roofless but extensive; a striking central courtyard has a yew tree and cloisters. The graveyard remains in use.