At left, runners make their way down 6th Street toward Independence National Historical Park in the early miles of the 2011 Philadelphia Marathon, Half Marathon & 8K, which saw more than 21,000 runners, walkers and wheelchair athletes cross the finish line and thousands more spectators line the streets.

The race takes runners through the area known as "America's most historic square mile," which features a run past the Liberty Bell and Independence Hall, where the founding fathers debated and approved both the Declaration of Independence and the U.S. Constitution. Later, runners make their way to the campus of the University of Pennsylvania and Fairmount Park, where they'll run along the banks of the Schuylkill River on the way back to the finish line near the Philadelphia Museum of Art.