Maps 18 Description and travel 17 Real property 17 Museums 16 History 15 Associations, institutions, etc 13 Directories 13 more ... Societies 13 Local transit 11 Societies, etc 10 Business enterprises 7 Economic conditions 7 Ethnic groups 6 Periodicals 6 Rents--Pennsylvania--Philadelphia Metropolitan Area 5 Transportation 5 Commerce 4 Mafia 4 Railroads 4 Regional planning 4 Social registers 4 Special libraries 4 Street-railroads 4 Central business districts 3 Commuting traffic 3 Guidebooks 3 Historic buildings 3 Library cooperation 3 Archives 2 Bicycle touring 2 Buildings 2 Churches 2 City traffic 2 College graduates 2 Debutantes 2 Ethnic relations 2 Finance, Public 2 Finance--Personal Expenses--19th century 2 Gardening 2 Historic sites 2 less ...