City in the Commonwealth of Pennsylvania in the United States, Philadelphia (often known as Philly) is a major financial and cultural centre. In 2020, it will have a population of 1,603,797 people, making it the sixth-most populous city in the United States as well as the most populated city in Pennsylvania. Aside from that, it is the second most populated city in the Northeastern United States, behind only New York City in population. Because it shares geographical boundaries with Philadelphia County, the city has had the same geographic boundaries for over 150 years. Philadelphia County is the most densely populated county in Pennsylvania and provides as the urban core of the eighth-largest ’s metropolitan area in the United States, with more than 6 million residents in 2017. Philadelphia is also the economic and cultural hub of the larger Delaware Valley, which encompasses the lower Delaware and Schuylkill rivers and is located within the Northeast megalopolis of New York City and Philadelphia. According to the most recent estimates, the Delaware Valley will have a population of 7.21 million people in 2019, making it the ninth-largest combined statistical region in the country.
While Philadelphia has developed into an intellectual and economic centre, the city's many institutions and colleges make it a popular study destination. At the end of 2019, the Philadelphia metropolitan region is expected to generate $490 billion in gross metropolitan product (GMP). There are five Fortune 1000 firms based in the city of Philadelphia, which serves as Pennsylvania's economic hub. As the city's skyline grows, the market for commercial properties grows as well, with about 81,900 commercial properties on the market in 2016, including some internationally recognised buildings. Unlike any other American city, Philadelphia boasts a higher concentration of outdoor sculpture and murals. When coupled with the nearby Wissahickon Valley Park, which is located in the same watershed, Fairmount Park constitutes one of the biggest continuous urban park areas in the United States, with a total land area of about 2,000 acres. As a result of the city's reputation for arts, culture, gastronomy, and colonial history, 42 million domestic visitors visited in 2016, spending a total of $6.8 billion, producing an estimated $11 billion in overall economic effect in the city and the surrounding four counties in Pennsylvania. Philadelphia is also a centre for biotechnology research and advancement.
Philadelphia is the site of several firsts in the United States, including the nation's first library (1731), hospital (1751), medical school (1765), national capital (1774), university (according to certain sources) (1779), stock exchange (1790), zoo (1874), and business school (1900). (1881). Independence Hall, a World Heritage Site, is one of the 67 National Historic Landmarks in Philadelphia. This is the first World Heritage City in the United States, and it became a member of the Organization of World Heritage Cities in 2015.