Britain has been building castles for over 3000 years and each one in turn was a state-of-the-art fortress. The castle was a place where power was based, and where law and order were dispensed, offering local populations protection from attackers. Yet it could equally be a site that was designed to instil fear and dread, and where terrible things happened to those who opposed the feudal lord. Throughout the centuries, castles fell into two types: The first were the fortresses that protected the coast and borders from the constant threat of invasion, and second were the inland baronial power bases where great estates were defended.

Fortress Britain makes an awe-inspiring journey around these buildings, travelling from the iron-age hill forts and Roman castles through the Norman and medieval castles to Tudor fortifications and Victorian coastal forts. The eye-catching exploration ends with the modern equivalent of castles – satellite listening stations and airfields for modern jet fighters. After 3000 years, Britain is still seen to defend its shores.

Part of the series Britain from the Air (8 x 60)