The original city of Philadelphia  outlined by founder William Penn consisted only of the area that is today known as Center City. The rectangular grid occupied approximately two square miles bordered by the Delaware and Schuylkill Rivers to the east and west, Vine Street to the north, and South Street to the south.
It wasn’t until 1854 that the city consolidated and all the boroughs, townships, and districts of the County of Philadelphia were incorporated into the city. Today, the city and county are one and the same, covering approximately 135 square miles. In addition to that neat grid of city blocks, the city now also includes hills, valleys, winding roads, rivers, creeks, and woodlands.
Water occupies just over 5 percent of the total area of Philadelphia, and parks and woodlands cover around 10 percent of the land area. The lowest point of the city is 10 feet above sea level at the meeting of the Delaware and Schuylkill Rivers in Southwest Philadelphia. The highest point is in Chestnut Hill, at 444 feet above sea level.
In addition to the two major rivers, the Delaware and the Schuylkill, smaller bodies of water include the Wissahickon, Cobbs, and Pennypack Creeks. Covering more than 9,200 acres, Fairmount Park is considered the largest urban municipal park in the world.
The largest continuous sections of the park are East and West Fairmount Parks, on either side of the Schuylkill River, the Wissahickon Valley Park in the northwest section of the city, and Pennypack Park  in the northeast, but the park system includes a total of 63 regional and neighborhood parks, including the five central city parks—Center, Franklin, Logan, Rittenhouse, and Washington—that were laid out in Penn’s original plan. Pretty much every patch of green in the city is part of Fairmount Park.
The second-largest city on the East Coast and the sixth-largest in the nation, Philadelphia  is conveniently located in the middle of the Northeast Corridor. By car, Philadelphia is approximately two hours from New York City and two and a half hours from Washington, D.C. It is an hour’s drive from Lancaster County, also known as Amish Country, and an hour from Atlantic City, New Jersey, with the rest of the New Jersey shore points just beyond.
The area known as the Greater Philadelphia region consists of five counties in southeastern Pennsylvania (Bucks, Chester, Delaware, Montgomery, and Philadelphia). The four counties in southern New Jersey (Burlington, Camden, Gloucester, and Salem) and New Castle County in Delaware are also sometimes included when referring to the Greater Philadelphia region.