Bridge building--19th century 3 Bridges--Philadelphia, PA--19th century 3 Bridges--Pennsylvania--19th century 2 Delaware River Bridge 2 Architecture--20th Century 1 Benjamin Franklin Bridge 1 Bridges, Construction--Pennsylvania and New Jersey 1 more ... Bridges--Delaware River--20th century 1 Bridges--Maintenance and repair 1 Bridges--Philadelphia--19th and centuries 1 Canals and railroads--19th century 1 Centennial Exhibition (1876 : Philadelphia, Pa.) 1 Committee on Alleged Decadence of the Port 1 Delaware & Schuylkill Canal 1 Delaware River Bridge Joint Commission 1 Engineering--Pennsylvania--Philadelphia 1 Hog Island Philadelphia Airport Terminal 1 Internal Improvements--19th century 1 Internal Improvements--Bridges--Pennsylvania 1 Investment--19th Century 1 McCall's Ferry--Lancaster County (Pa.)--19th century 1 Mills, Robert 1 Pennsylvania Railroad--19th century 1 Philadelphia views--Street scenes--20th century 1 Philadelphia--Board of Trade--Records and Correspondence 1 Railroads--Design and construction 1 Railroads--Pennsylvania--19th century 1 Schuylkill River (Pa.) 1 Schuylkill River Views--Late 19th century 1 Separation and divorce--19th century 1 Smallpox--Pennsylvania--Philadelphia 1 Wissahickon (Philadelphia, Pa.)--Bridges 1 Wissahickon (Philadelphia, Pa.)--Buildings 1 Wissahickon (Philadelphia, Pa.)--Landscapes 1 less ...