Groupe fortifié du Saint-Quentin/Feste Prinz Friedrich-Karl is a group of two forts and various facilities in the inner belt of fortifications around Metz.
It started with the construction of Fort Diou between 1867 and 1870 by the French army. In 1870 the Franco-Prussian War broke out and in 1871 Metz was annexed by the German Empire. The Germans renamed the fort to Feste Prinz Friedrich-Karl and built additions between 1872 and 1892. About 1200 meters west of the original fort they built a new fort, called Fort Manstein. In between the two forts many more facilities were built, such as a two-story barrack, an ammunition depot, two gun batteries, a heavy mortar position and an armoured battery with two armoured cupolas for 21cm-Granatwerfers manufactured by Krupp. For transportation an extensive railway system was made.
Metz officially got liberated on 22 november 1944, but the German soldiers in Feste Prinz Friedrich-Karl kept defending for two more weeks as ordered by Hitler. They were slowly running out of resources, on 6 december 1944 they finally had to surrender and the United States Army disarmed the forts. Since then, Groupe fortifié du Saint-Quentin stands forgotten and crumbling under the forces of nature.
Unfortunately the harsh sunlight and lots of vegetation made it very hard to photograph. Still the place is so impressive that I hope it makes up for the mediocre photos.