Fort des Dunes

The Fort des Dunes, also known as Fort Leffrinckoucke and sometime Fort de l'Est, is located in the commune of Leffrinckoucke, France, about 6 kilometres east of Dunkirk. Built from 1878 to 1880, it is part of the Séré de Rivières system of fortifications that France built following the defeat of the Franco-Prussian War. Although it played no part in World War I, it had a significant role in both the beginning and end of World War II. It has been preserved and is interpreted by a local preservation association for the public.

Source: Wikipedia