Here's the real answer, tell your friend (and no, it's not straight forward)
Metallica was formed in Los Angeles and made some recordings as a band from LA. But when they wanted to add Cliff Burton to the band, he said he'd only join if they moved to San Francisco.
They recorded a few songs as an "LA" band, but never released an album until becoming a "SF" band.
That's the story, interpret how you will.
p.s. to me, they're a San Francisco band.