Grande Mosquée de Paris

Look up at that minaret. It rises 33 meters into the Parisian sky, and it has stood here since the 1920s, built as a tribute to the 100,000 Muslim soldiers who died fighting for France in the First World War. Most came from Algeria, Morocco, and Tunisia. The French state paid for all of it, making a quiet exception to its own strict law separating church and state.

Architect Maurice Tranchant de Lunel drew his inspiration from the Alhambra palace and the great mosque of Fez. Step inside the courtyard and you will see why. The tilework, the carved plaster, the fountain at the center, it feels like a city within a city.

But the most extraordinary chapter happened underground. During the Nazi occupation, the mosque's rector, Si Kaddour Benghabrit, sheltered roughly 1,600 Jews, resistance fighters, and British paratroopers. He gave them false Muslim identity papers, carved their names onto gravestones as cover stories, and helped them escape through tunnels connected to an old underground river called the Bièvre.