Mont Saint-Michel is a granite mount a kilometre off the coast of Normandy, in northern France, crowned by an abbey that has stood there since 708. Everything about the place comes from the bay around it. As the tide pushes in from the west the coast narrows like a funnel, and the seabed drops barely a metre for every kilometre. The water has nowhere to spread, so it piles up instead. These are the highest tides in continental Europe, and the sea withdraws some fifteen kilometres and comes back across the flats twice a day. That is why a sanctuary made sense on this rock, and why an army never took it. The abbey began with a bishop who would not listen. Three times the archangel Michael told Aubert of Avranches to build here, and on the third, tradition says, an impatient Michael pressed a finger to the sleeping bishop's head and left a small round hole in it. A pierced skull is still shown as Aubert's in Avranches.
Through the island's one gate the Grande Rue climbs steep and cobbled between medieval houses, inns and shops, up to the abbey at the summit. The bare Romanesque nave and the colonnaded cloister of La Merveille hold a stillness you do not expect this close to the sea. The west terrace opens the bay to the horizon. For seventy years after the Revolution none of it was a monastery. The state ran the abbey as a prison, and a great wooden wheel still stands in the monks' old ossuary, the one prisoners walked inside to haul their own food up the rock. From the terrace and the ramparts you watch the sea come back. After dark the floodlights wash the walls, and the gilded archangel on the spire catches the light. At low tide you can go out onto the flats yourself, barefoot on the wet sand, but only behind a licensed guide: the bay hides quicksand, and the water returns faster than anyone can outrun it.