Anyone who is interested and doesn't already have an extensive awareness of David Bowie's catalogue really owes it to him or herself to listen to The Rise and Fall of Ziggy Stardust and the Spiders From Mars. This a great fucking collection and even though Bowie was a mega-freak cum-guzzling weirdo when it was released, and even though I was born the same year it came out so I have zero historical perspective other than what has been regurgitated to me, I find this to be one of the greatest records of all-time. Ever.
This is before Bowie became an 80's/90's retread with a stupid, embarrassing haircut, too.
I would venture to guess that this album contains four of his best known songs (Five Years, Ziggy Stardust, Starman, Suffragette City), and really even beyond that it's a masterpiece when viewed as a single, organic piece, discounting the singular components themselves.
Just listen to the record already. You'll be doing yourself a disservice not to.