Philadelphia - Pennsylvania’s largest city, is notable for its rich history. It is the fifth-most-populous in the United States, with an estimated population in 2014 of 1,560,297. In the Northeastern United States, at the confluence of the Delaware and Schuylkill River, Philadelphia is the economic and cultural anchor of the Delaware Valley, a metropolitan area home to 7.2 million people and the eighth-largest combined statistical area in the United States. It is also home to many national historical sites that relate to the founding of the United States. Independence National Historical Park is the center of these historical landmarks being one of the country's 22 UNESCO World Heritage Sites.Independence Hall, where the Declaration of Independence was signed, and the Liberty Bell are the city's most famous attractions.