When Fadi and Majid Boustany took the keys to their father’s palatial Hôtel Metropole in 2001, the brothers knew the place needed some modern love. Despite its enviable location across from Monte Carlo’s casino, the 1886 Italian Belle Époque building hadn’t been lit up by a Paris Match flashbulb in decades. To bring the buzz back—and to lure a young clientele—the Boustanys hired Jacques Garcia, designer of Paris’s nouveau-baroque Hôtel Costes. Tapestries and low-slung seating now sex up public spaces, while guest rooms mix Pierre Frey fabrics with ornamental columns and slate-and-wood bathrooms. Celebrity chef Joël Robuchon has installed a namesake restaurant, serving dishes such as crab atop citrus tabbouleh and grands crus by the glass. And to welcome those paparazzi back, the long, landscaped driveway ends at a 26-foot-high boxwood Arc de Triomphe.