“For twenty-two years, the photographer Josef Astor (no relation) has had a studio above the stage at Carnegie Hall. It’s on the eighth floor, although technically the eighth is below the seventh; to get to it you take an elevator to six and walk up half a flight of stairs. The Carnegie Hall Studio Towers, as these quarters over the concert hall are known, contain many such oddities, but they also harbor one Manhattan commonplace: a band of artist-occupants whose tenancy is venerable, tenuous, and probably doomed.”