San Francisco, as any local knows, is being besieged by an invasion force. The hordes' uniforms and accouterments are easy to spot: Horrible “Alcatraz Psycho Ward” T-shirts, ubiquitous maps, and guidebooks that lead them to Fourth and King when they're seeking Pier 39 with eerie regularity.
These international invaders are the lifeblood of the city. Much capital has been expended to look after then and keep them coming. More than a century ago, however, the government invested heavily in a project that would offer a different manner of welcome to foreigners. Specifically, it aimed to blow them up.