The Fort can be visited
Citadelle de Blaye
The Citadelle de Blaye, a 17th-century fortress, is located on the eastern bank of the Gironde in Blaye, France. It was constructed to protect the port of Bordeaux.
History+
The origins of fortifications at this site date back to Roman times, when a castrum was present. Later, the Merovingian king Charibert II ordered the construction of a castle. In the 12th century, a medieval castle complex was built under Wulgrin Rudel, whose ruins, known as Château des Rudel, are still visible today and were partially integrated into later expansions. The first major fortification expansion began in 1652 under the direction of Blaise François Pagan.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Cit_Blaye_porte_Dauphine_2.JPG?uselang=fr
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 45.1293, -0.6664