) is a city in the Commonwealth of Pennsylvania in the United States, and is the county seat of Allegheny County.As of 2017, a total population of 305,704 lives within the city limits, making it the 63rd-largest city in the U. The metropolitan population of 2,353,045 is the largest in both the Ohio Valley and Appalachia, the second-largest in Pennsylvania (behind Philadelphia), and the 26th-largest in the U. Located at the confluence of the Allegheny, Monongahela, and Ohio rivers, Pittsburgh is known as both "the Steel City" for its more than 300 steel-related businesses, and as the "City of Bridges" for its 446 bridges.During 1753–54, the British hastily built Fort Prince George before a larger French force drove them off.The French built Fort Duquesne based on La Salle's 1669 claims.The city features 30 skyscrapers, two inclined railways, a pre-revolutionary fortification and the Point State Park at the confluence of the rivers.The city developed as a vital link of the Atlantic coast and Midwest, as the mineral-rich Allegheny Mountains made the area coveted by the French and British empires, Virginians, Whiskey Rebels, and Civil War raiders.By the terms of the 1768 Treaty of Fort Stanwix, the Penns were allowed to purchase the modern region from the Iroquois.
Lord Jeffrey Amherst ordered blankets contaminated from smallpox victims to be distributed in 1763 to the tribes surrounding the fort.
European pioneers, primarily Dutch, followed in the early 18th century.
Michael Bezallion was the first to describe the forks of the Ohio in a 1717 manuscript, and later that year European fur traders established area posts and settlements.
The British and colonial force were defeated at Braddock's Field.
General John Forbes finally took the forks in 1758.