Design and construction Railroads 34 Bridges 21 Roads 18 Costs 17 History 17 Canals 11 more ... Prisons 8 Buildings 5 Buildings, structures, etc 5 Cars 4 Hospital buildings 4 Locomotives 4 Prison administration 4 African Americans 3 Electric railroads 3 Engineers 3 Museums 3 Public buildings 3 Railroad bridges 3 Streets 3 Surveying 3 Architects 2 Biography 2 CHR 1789 2 Charities 2 Charity organization 2 City planning 2 Conception et construction 2 Concrete construction 2 Conservation and restoration 2 Electric power-plants 2 Endowment of research 2 Endowments 2 Equipment and supplies 2 Historical museums 2 Hospitals 2 Humanitarianism 2 Iron and steel bridges 2 Law and legislation 2 less ...