http://tags.library.upenn.edu/cobine/infrastructure+cityblocks PennTags Feed for /cobine/infrastructure+cityblocks PennTags Feed http://tags.library.upenn.edu/makerecord/url/40197 http://tags.library.upenn.edu/makerecord/url/40197 Digital Sanborn Maps - Pennsylvania http://tags.library.upenn.edu/makerecord/url/40191 http://tags.library.upenn.edu/makerecord/url/40191 Architectural Research at the Philadelphia City Archives