Each stage of developement of the mount marked a great event in the history of Normandy. The beginnings in 966 marked the expansion of normandy to take in Mont St Michel. The Norman abbey was built under the influence of the rise of power under Wiliam.
In 1204 the english kings who had ruled over Normandy since William became King of England, were pushed out of Normandy by Philip August. To mark this great event he finaced a great project at mont St Michel.
Walls were made thinner and higher with larger openings. The main construction was the three story Monastry complex called the Marvel.