Perched on the highest point in the western Paris suburbs, this massive 1840s fortress has a grim second life as France's most important WWII resistance memorial. During the Occupation, the Germans used the fort as their primary execution site for the Île-de-France, killing over a thousand hostages and resistance fighters in the clearing below the ramparts.
The Mémorial de la France combattante, inaugurated by de Gaulle in 1960, occupies the slope facing Paris. Sixteen bronze reliefs represent the different forms of French resistance, and an eternal flame burns in the crypt. The memorial is free and always accessible. The fort itself can be visited on guided tours (usually weekends), which take you through the execution clearing, the chapel where prisoners spent their last night, and the fortifications themselves. It's a sobering, powerful site — not a casual stop, but essential for anyone interested in the war years. The fort is technically in Suresnes, about 3 km east of central Rueil-Malmaison.