In the early 12th century AD, a large part of what we now think of as France was not under the direct control of the French King who's authority stretched little further than Paris. One region of Southern France, the Languedoc, became the centre of Catharism - heresy in the eyes of the Pope - who ordered a crusade against the region. The crusading army of French knights seized the opportunity to gain land and riches and the crusade was a viciously waged. The inhabitants of the Languedoc had always relied for their safety upon as series of strongly fortified walled cities - Albi, Carcassonne, Beziers, Toulouse - as well as a large number of fortified hill-top villages and castles, 'castra', which dotted the countryside. This book will describe the so-called 'Cathar castles', why they were positioned where they were, how they were built, how well those they withstood the realities of the Albigensian Crusade.