Flickering cube fire pits flank an infinity pool that faces the sea at this hillside villa redesigned by a prominent French architect in 2017. Hosting celebrities from the Kennedy family to singer Mariah Carey, the home radiates charm—a pizza oven, breeze-swept hammock, glass-walled wine cellar. Hit the private gym, shower and dine alfresco, and find yourself at St. Jean Bay less than a mile away.