From prehistoric hill forts to grand medieval castles and from gentlemen's fortified country homes and Victorian follies to the defensive installations of World War II, the whole range of fortifications built in Britain is examined through the remains that can be found in every corner of the island. Beginning with the great hill forts of prehistory, the historical development of British fortifications is plotted through the legacy of the Roman occupation and the strongholds of the Dark Ages to the hastily-erected motte and bailey castles of the Normans and the magnificent fortresses of the Middle Ages. It continues through the essential coastal fort-building exploits of Henry VIII and Elizabeth I to the remarkable sea forts and Martello towers of the 19th century and on to the pillboxes and underground nuclear shelters of the 20th century.