The best place to find maps and a wealth of information about what to do and where to go in Philadelphia [1] is at the Independence Visitor Center [2] (6th and Market Sts., 215/965-7676 or 800/537-7676, www.independencevisitorcenter.com [3]). It is conveniently located in Old City near the major historic attractions. The large facility has knowledgeable staff and volunteers, as well as exhibitions, a film theater, café, gift shop, and bookstore.
Links:
[1] http://www.moon.com/destinations/philadelphia/discover-philadelphia
[2] http://www.moon.com/destinations/philadelphia/sights/old-city/independence-national-historical-park/independence-visitor-center
[3] http://www.independencevisitorcenter.com