Tutto sotto controllo”—everything’s under control—Diego Della Valle observed contentedly, to no one in particular, on a bright recent morning as he strolled into Rome’s Colosseum, which was empty except for a photography crew busily preparing to take his portrait. Off-hours access inside Italy’s most famous monument is a nice perk that comes with p...

For Diego Della Valle, the 63-year-old billionaire owner of Italian luxury leather and apparel giant Tod's Group, style has always trumped fashion. Considering the success Tod's has had since its formation in 1978, Della Valle has a point.