Standing in the center of Place de la Concorde, with your back to the Seine, you can’t miss three wonderful monuments: the Hôtel de Crillon (a palace hotel), the Madeleine church at the end of rue Royale, and the Hôtel de la Marine, the 18th-century neoclassical beauty (the Crillon’s twin) that once stored the king’s furniture before becoming the naval ministry’s HQ. Its history is fascinating: here, in 1792, France’s crown jewels—more than 10,000 gemstones of diamonds, topazes, rubies, emeralds, sapphires, and pearls—were stolen under the guards’ noses. In 1848, it was here that minister François Arago abolished slavery in the colonies. For years the building was off-limits to the public, but in 2021 it opened as a museum, with period rooms showcasing 18th-century design, hitherto unseen royal furniture, and the Qatarian Al Thani Collection, an assembly of over 6,000 works of art, including the 17th-century Idol’s Eye, the world’s largest blue diamond. The museum’s inner courtyard is open to the public from 9am to midnight and displays contemporary floor lights that at night make you feel as though you’re walking on stars.