The original monastery is said to have been founded by St. Bruno. It consisted merely of a humble chapel and a few isolated cells, which are supposed to have occupied the site in the _Desert_, on which the Chapels of St. Bruno and St. Mary now stand. The existing buildings were reconstructed in the sixteenth and seventeenth centuries in the manner of the day, of which the arcades of the great cloister are good examples. The present church, which is extremely simple in design, has preserved nothing of its sixteenth-century decoration but the choir stalls. The great cloister consists of an arcaded gallery, on which the sixty cells of the monks open. It is arranged in strict accordance with the Rule of St. Bruno as regards its connection with the main buildings, the chief features of which we have already pointed out. CHAPTER IV FORTIFIED ABBEYS The monasteries built throughout the twelfth century were provided with outer walls, by means of which the claustral buildings, offices, workshops, and even farms of the community were enclosed. Thus all the necessaries of life were produced within the precincts, and all communication with the outside world was avoided. But by the end of the century the great abbeys had become feudal castles; and fortified walls were raised around them, often embracing the town which had grown up under their protection and shared their fortunes. This was the case at Cluny, and the town acknowledged its obligations to the monks by the payment of tithes. In the reign of Philip Augustus and St. Louis the abbots were not only the heads of their monasteries but feudal chieftains, vassals of the royal power, and as such obliged to furnish the sovereign with men-at-arms in time of war, and to maintain a garrison when required.[52] [52] See Part III., "Military Architecture," Abbey of Mont St. Michel. The Abbey of Tournus was, like Cluny, surrounded by walls connected with the city ramparts. The Abbey of St. Allyre, in Auvergne, near Clermont, was defended by walls and towers, which seem to have been added to the original structure of the ninth century at some period during the thirteenth, when such fortification of religious houses became necessary. [Illustration: 149. ABBEY OF MONT ST. MICHEL. GENERAL VIEW FROM THE ROCKS OF COUESNON, TAKEN IN 1878, BEFORE THE CONSTRUCTION OF THE DYKE] In many other monasteries a system of defence more or less elaborate was adopted; but the most famous of all the abbeys built by the Benedictines was unquestionably Mont St. Michel, which, for boldness and grandeur of design, is unique among military and monastic monuments from the eleventh to the close of the fifteenth century. [Illustration: 150. ABBEY OF MONT ST. MICHEL. PLAN AT THE LEVEL OF THE GUARD-ROOM, ALMONRY, AND CELLAR