Most of the buildings at the Philadelphia Navy Yard have been restored, but with several hundred on the base, it’s not surprising that some still sit vacant. And a good thing, too, for our purposes at least. The things people leave behind make for great photo subjects, which is why we were thrilled to be able to hold a photo workshop there in November taught by Abandoned America’s Matthew Christopher. The images everyone came back with were so spectacular, we decided to feature them in the Hidden City Daily. The more industrial photos come from Building 18, a Renaissance Revival beauty that was originally used as a boiler and blacksmith shop. The images of office equipment are from Building 83, an eight-story concrete structure with a suite of offices on the top two floors built in 1919 to be a general storehouse.