Worldly Philadelphian

In case you're interested in history beyond Philadelphia...

You can certainly use many of the tools described with respect to Philadelphia, but here are some others.

Archival tools:

World Digital Library (UNESCO, et al)
http://www.wdl.org/en

Global Gateway (Library of Congress)
http://international.loc.gov/intldl/intldlhome.html

Ready, 'Net, Go! Archival Internet Resources
http://www.tulane.edu/%7Elmiller/ArchivesResources.html

UNESCO (United Nations) Archive Portal
http://www.unesco.org/webworld/portal_archives

Eurodocs
http://eudocs.lib.byu.edu/index.php/Main_Page

Resources to find libraries:

Internet Public Library
http://www.ipl.org/

The WWW Virtual Library
http://vlib.org/

National Library Catalogues Worldwide
http://www.library.uq.edu.au/natlibs/

World Wide Web Library Directory
http://travelinlibrarian.info/libdir/

Libraries around the world (for example):

British Library
http://www.bl.uk/

Deutsche Nationalbibliothek
http://www.ddb.de/

Harvard University
http://lib.harvard.edu/

La Sorbonne
http://www.paris-sorbonne.fr/en/spip.php?rubrique53

Other tips:

• look for archives local to your topic (city or state or university) and search those
• look for the national library or archives of the relevant country
• try google: google books, google scholar, and carefully chosen keywords in regular google