Def Leppard kicked off a new Las Vegas residency this week. We take you inside opening night.

Which rock acts have found it impossible to retire? When has the curtain come down on a stellar career... only to come up again, just a couple of years later?

“And then he played me the whole Mercyful Fate medley down the phone. He said, ‘What do you think?’ I said, ‘Are you kidding?