Rindoon Castle, Lough Ree, Co Roscommon

Rindoon is built on a fortified peninsula, St John's Point (near the village of Lecarrow), on the western shore of Lough Ree. The castle was built in the 13th century to protect an Anglo-Norman town that once had a population of c.1000 inhabitants.

The abandoned town is one of Ireland's most important medieval heritage sites, with access via a great loop-walk, or by boat on the Shannon navigation system. It has an excellent website