The Cézon island is accessible at low tide and is part of a set of islets, some of which are well known: Guennioc (prehistoric vestiges), Stagadon (old farm of goemonniers), island Virgin (the highest lighthouse in Europe), the Wrac'h island ' h (semaphore, residence of artists), the island to the Americans (former base for seaplanes during the 1st World War).
The walled part occupies 1/3 of the Cézon island.
The fortifications surround were first constructed by Vauban from 1694 and transformed over the centuries – especially under Napoleon III – up to the second world war, during which 17 blockhouses were erected.
The site is registered historical monument since July 2015.
You can download the current state of the places, in 3 documents:
And on the history, you will know almost everything that we know by going here, on the site of the Brittany Region