Design and construction 129 History 35 Railroads 35 Bridges 23 Construction industry 23 Construction 19 Roads 19 more ... Costs 17 Buildings 16 Canals 14 Buildings, structures, etc 11 Constructions 10 Interpretation and construction 9 African Americans 8 Prisons 8 Streets 8 Employment 6 Histoire 6 Concrete construction 5 Museums 5 Subways 5 Transportation 5 Architects 4 Architecture 4 Canal construction--19th century 4 Cars 4 Construction navale 4 Engineering and construction 4 Hospital buildings 4 Locomotives 4 Organ (Musical instrument) 4 Prison administration 4 Shipbuilding 4 Tunnels 4 Architecture, Domestic 3 Biography 3 Building materials industry 3 Canals--Pennsylvania 3 Construction work--Philadelphia--19th century 3 Electric railroads 3 less ...