This book is a comprehensive guide to castles, fortified houses, bawns and town defences in the twelve counties of the eastern and south-eastern parts of Ireland which make up the province of Leinster. An introduction describing the development of castellated buildings of stone in Leinster, dating from the 12th century to the mid 17th century is followed by twelve gazetteers describing the history and architectural features of over 350 such buildings in the counties of Carlow, Dublin, Kildare, Kilkenny, Laois, Longford, Meath, Offaly, Westmeath, Wexford and Wicklow. The gazetteers are illustrated with many plans, drawings and photographs and there is a map showing the location of surviving buildings. Lists at the ends of the gazetteers provide summary information on 300 other buildings, as well as sites of lost castles.