Downtown's last prewar bars are splendid slices of early San Francisco history.

Downtown's last prewar bars are splendid slices of early San Francisco history.

San Francisco is constantly remaking itself, evolving from generation to generation. Most businesses don’t survive this passage of time—relentless and unyielding. But those that do? They’re something special. They’ve become living repositories of the city’s past.Downtown, in some of SF’s oldest neighborhoods, you can still find many of the city's most enduring landmarks—especially bars and saloons, which have been remarkably successful at standi…