Paul McCartney -- excuse us, Sir Paul McCartney -- hit American shores as part of the mop-topped Beatles almost 50 years ago. And music has never been the same since.

Heavily influenced by Buddy Holly, Little Richard and Elvis Presley, the Beatles toiled in European clubs before making it big, and were even famously rejected by a record company rep who told them, "Guitar groups are on the way out." (We're guessing that guy didn't have a terribly long career in the music industry.)

The Fab Four took the U.S. by storm in early 1964 -- the photo on the left was taken around then -- and were only together for about 10 years from hard-scrabble start to Yoko-influenced finish, but that's all it took to cement their place in music history.

With estimated sales of over one billion units, it would've been easy for Sir Paul to retire and enjoy his legacy -- and yet, he's done anything but. He's had an enormously successful career with Wings and as a solo artist, and his most recent effort, the rather unfortunately-named 'Kisses on the Bottom,' reached No. 5 on the charts after its release last month.

And even at 69 years old, his boyish face hasn't changed all that much. The impish grin that made millions of teenaged girls swoon? Still present and accounted for.