For as long as tourists have visited William Penn's City of Brotherly Love, Independence National Historic Park has been the focus of their attention – and rightly so, seeing as how "America's most historic square mile" is home to Independence Hall, Liberty Bell Center, Declaration House and Christ Church Burial Ground. For narrated insight about the sites, hook up with Constitutional Walking Tour or another of the city's reputable guide companies, or you can just do it the Ben Franklin way: on your own, with only your wits and common sense to guide you. While each of the Revolutionary-era sites is a must-see, especially for history buffs, there are plenty of other ways to burn your daylight hours here. For starters, art-lovers should plan a stop by the Museum of Art, whose permanent collections include pieces by Dali, Max Ernst and Canaletto. The wonders of science, meanwhile, are the focus of the esteemed Franklin Institute, and the Philadelphia Zoo is the oldest in the US yet remains ever-popular with the kids.