The Abbey of Mont St. Michel was founded in 708 by St. Aubert, according to tradition. At the close of the tenth century it was restored by Richard Sans Peur, third Duke of Normandy, with the help of the Benedictine monks from Monte Casino, whom he had installed at St. Michel in 966. It increased greatly in wealth and extent in the eleventh century, and by the end of the twelfth was in the full tide of its prosperity. Its buildings, however had not yet that importance to which they attained in the following century.[53] In the twelfth century they consisted of the church, which was built between 1020 and 1135[54] and the monastic buildings proper (_lieux réguliers_), with lodgings for servants and guests to the north of the nave, at G, G´, and F on the plan, Fig. 152. To these, which were restored or reconstructed in a great measure by the Abbot Roger II. at the beginning of the twelfth century, additions were made on the south and south-east by Robert de Thorigni from 1154 to 1186. The monastery was not then fortified. [53] _Description de l'Abbaye du Mont St. Michel_, by Ed. Corroyer; Paris, 1877. This work was crowned by the Institute in 1879, at the _Concours des Antiquités Nationales_. [54] See _L'Architecture Romane_, by Ed. Corroyer; Paris, Maison Quantin, 1888. [Illustration: 152. ABBEY OF MONT ST. MICHEL. PLAN AT THE LEVEL OF THE UPPER CHURCH, THE CLOISTERS, AND THE DORMITORY _Key to Plan._--A, A´, A.´´ Church, choir, and transepts. B, B´, B´´. Three first bays of nave, destroyed in 1776. C, C´, C´´. Towers and porch (Robert de Thorigni). D. Tomb of Robert de Thorigni. E. Formerly the terrace in front of the church. F. Formerly the chapter-house. G, G´. Formerly the claustral buildings. Dormitory. H. Platform at the southern entrance of the church. I. Ruin of the hostelry (Robert de Thorigni). J. Infirmary. K. Dormitories of the thirteenth century (_Merveille_). K´. Tower, known as the _Tour des Corbins_ (thirteenth century, _Merveille_). L, L´. Cloister and archives (thirteenth century, _Merveille_). M. Vestry (thirteenth century, _Merveille_). N. Abbot's lodging. O. Accommodation for guests. P. Courtyard of the _Merveille_. P´. Terrace of the apse. Q. Courtyard of the church and great staircase.]