In an area of largely spurious "heritage", the 12-Bar Club is one of the few places that I'll be sad to see vanish.
Almost any documentary you can see about the music scene in London in the 60s will have footage of either a band playing in there, or of punters queuing outside it.
But the Marquee left Wardour Street many years ago, the Astoria was demolished a few years back, and somehow the contemporary London music scene seems to have survived.