Originally Posted by Wikipedia
Mont Saint Michel is a small rocky islet, roughly one kilometer from the north coast of France at the mouth of the Couesnon River, near Avranches in Normandy, close to the border of Brittany. It is home to the unusual Benedictine Abbey Church (built between the 11th and 16th centuries) which occupies most of the one kilometer diameter clump of rocks jutting out of the ocean.
It is connected to the mainland via a thin natural land bridge, which before modernization was covered at high tide, and revealed at low tide. Thus, Mont Saint Michel gained a mystical quality, being an island half the time, and being attached to land the other : a tidal island.
However the insular character of the mount has been compromised by several developments. Over the centuries, the coastal flats have been polderised to create pasture. The coast south of the mount has thus encroached on the distance between the shore and the mount. The river Couesnon has been canalised, reducing the flow of water and thereby encouraging a silting-up of the bay. In 1879, the land bridge was fortified into a true causeway. This prevented the tide from scouring the silt round the mount. Now there are plans to remove the causeway and replace it with a ferry.
Before the construction of the first monastic establishment in the 8th century, the island was called Mont Tombe. According to legend, the archangel Michael appeared to St. Aubert, bishop of Avranches, in 708 and instructed him to build a church on the rocky islet. Aubert repeatedly ignored the angel's instruction, until Michael burned a hole in the bishop's skull with his finger.
The mount gained strategic significance in 933 when the Normans annexed the Cotentin Peninsula, thereby placing the mount on the new frontier with Brittany. Ducal and royal patronage financed the spectacular Norman architecture of the abbey in subsequent centuries.
The wealth and influence of the abbey extended to many daughter foundations, including St Michael's Mount. However, its popularity and prestige as a centre of pilgrimage waned with the Reformation and by the time of the French Revolution there were scarcely any monks in residence. The abbey was closed and converted into a prison, initially to hold clerical opponents of the republican régime. High-profile political prisoners followed, but by 1836 influential figures, including Victor Hugo, had launched a campaign to restore what was seen as a national architectural treasure. The prison was finally closed in 1863, and the mount was declared a historic monument in 1874.
The tides in the area shift quickly, and has been described by Victor Hugo as "à la vitesse d'un cheval au galop" or as swiftly as a galloping horse. However, this is an exaggeration, as the tide actually comes in at 1 metre per second.
The tides can vary greatly, at roughly 14 meters between high and low water marks. Popularly nicknamed St. Michael in peril of the sea by mediaeval pilgrims making their way across the tidal flats, the mount can still pose dangers for visitors who avoid the causeway and attempt the hazardous walk across the sands from the neighbouring coast. The dangers from the tides and quicksands continue to claim lives.
The mount is the object of traditional, but nowadays good-humoured, rivalry between Normans and Bretons. Bretons claim that, since the river Couesnon marks the traditional boundary between Normandy and Brittany, it is only because the river has altered its course over the centuries that has placed the mount on the Norman side of the frontier. Normans display a certain proprietorial pride in the mount - for example, the département of Manche in which the mount is situated uses its silhouette in its logo - and affect mild irritation on occasions when Brittany uses the mount in tourist publicity.