This L-shaped 45-acre park , along with Old City, has been dubbed 'America's most historic square mile.' Once the backbone of the United States government, today it is the backbone of Philadelphia's tourist trade. Stroll around and you'll see storied buildings in which the seeds for the Revolutionary War were planted and the US government came into bloom. You'll also find beautiful, shaded urban lawns dotted with large groups of schoolchildren and costumed actors. Most sites are open every day from 9am to 5pm, and some are closed Monday. Note that you must call or stop in to the Independence Visitor Center to make a timed reservation before visiting the high-volume Independence Hall, and beware that lines for the Liberty Bell can be extremely long.