Fort National is a fort on a tidal island a few hundred metres off the walled city of Saint-Malo. The great military architect Vauban had it built in 1689 to protect Saint-Malo's port.
The fort was originally called Fort Royal. In 1789 the fort's name became Fort d'Îlette or Républicain, then Fort Impérial and, after 1870, Fort National.
Wikipedia https://en.wikipedia.org/wiki/Fort_National
Official Website https://www.fortnational.com/en/
Address 35400, France
Coordinates 48°39'17.472" N -2°1'23.857" E