File:Saint-Martin chapel inside of the Benedictine abbey - Mont St Michel (32799924761).jpg

Started during the 10th century, the Benedictine abbey has numerous architectural marvels from West Roman empire, roman and Gothic styles. The Mont-Saint-Michel could, in that sense, be considered a megastructure where the buildings are on top of each other while trying to accommodate Benedict activities within a tight space. The abbey can be divided in multiple parts. The original church-abbey was founded in 966 but later completely covered by the multiple expansions of the abbey and was then forgotten for many centuries. These parts of the abbey were rediscovered near the end of the 19th and beginning of the 20th century. It has since been restored and offers a beautiful example of pre-roman architecture.

As more pilgrims came to the Mont Saint Michel, it was decided to expand the abbey by building a new abbey church at the site of the monks' quarters, which was moved to the north of Notre-Dame-Sous-Terre.

The new church-abbey first had three crypts built: the Trente-Cierges chapel (under the North wing), the choir crypt (to the East) and Saint-Martin chapel (under the South wing) (1031-1047). Then Abbot Ranulphe started the construction of the nave in 1060. In 1080, three levels were built to the North of Notre-Dame-Sous-Terre, including the "salle de l’Aquilon", which served as chaplaincy to host pilgrims, the monk promenade and a dormitory. The wine cellar and chaplaincy for the future "Merveille" were also started.

The other church-abbey buildings were erected to the East of the original church, on top of the rock and above the church itself.

The Mont-Saint-Michel abbey is divided in two parts: the church-abbey and the "Merveille". The "Merveille" was the monk living area. Seen from outside, it has a gothic front, on the North side, has three levels and was built over 25 years. The "Merveille" can be subdivided into two parts: the East and the West sides. The East side was built first (from 1211 to 1218) and has three rooms: the chaplaincy, the hosts room and the dining-hall (from bottom to top). The West side was built seven years later and has three rooms: the wine cellar, the Knights room and the cloister.