The Vatican of Western Railroading - 65 Market St.

California Street Cable Car near the line's terminus, with Southern Pacific's headquarters building in the background.

Espee's headquarters building may have actually been One Market Street at the date of the photo, although the 65 Market address existed far longer. I love the story I once read about how the office was so resistant to change, that paper clips did not appear in the office until the Sixties, papers being bound instead, by long pins, with frequent punctures of office worker's fingers. There are some great photos of the building and other San Francisco buildings here.