Pittsburgh (pronounced ˈpɪts.bɚg) is the second largest city in the Commonwealth of Pennsylvania. It is the county seat of Allegheny County, Pennsylvania. Built on land surrounding the confluence of the Allegheny and Monongahela rivers, where they merge to form the Ohio river, Pittsburgh features a skyline of 151 skyscrapers, 446 bridges, two inclines and a pre-revolutionary fortification. Residents of the city are called Pittsburghers. The downtown area is compact and walkable, located on the triangular parcel at the confluence of the rivers. Pittsburgh is noted for bridges of all types throughout the city and is commonly known as the "The City of Bridges" or "The Bridge Capital" of the U.S.

Pittsburgh's economy was fueled by heavy manufacturing until the 1980s when the domestic steel industry collapsed. The city's economy is now largely based on healthcare, education, technology and financial services. Robotics, in particular, is a major sector of the local economy. The Wall Street Journal dubbed the city "Roboburgh."

Despite a declining population, Pittsburgh remains the principal cultural and economic influence in the eastern Ohio River Valley. Because of its low cost of living, economic opportunities, education, transportation and medical infrastructure, Pittsburgh is consistently ranked high in livability surveys. In 2007, Pittsburgh was named "America's Most Livable City" by Places Rated Almanac.

History

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The first Europeans arrived in the 1710s as traders. Michael Bezallion was the first to describe the forks of the Ohio in a manuscript in 1717, and later that year European traders established posts and settlements in the area. In 1749, French soldiers from Quebec launched a serious expedition to the forks in hopes of uniting French Canada with French Louisiana via the rivers. Governor Dinwiddie of Virginia sent Major George Washington to warn the French to withdraw. During 1753–1754, the English hastily built Fort Prince George, but a larger French expedition forced them to evacuate and constructed Fort Duquesne on the site. These events led to the French and Indian War. British General Braddock's campaign (with Washington as second-in-command) to take Fort Duquesne failed, but a year later General John Forbes's subsequent campaign succeeded. After forcing the French to surrender Fort Duquesne in 1758, he ordered the construction of Fort Pitt, named after British Secretary of State William Pitt the Elder. He also named the settlement between the rivers "Pittsborough."

During Pontiac's Rebellion, Ohio Valley and Great Lakes tribes besieged Fort Pitt for two months. Fort Pitt, unlike Detroit, Mackinac, and other major forts on the frontier, was the only one to withstand the Indian uprising and not surrender. In many ways, it was Fort Pitt that ensured westward expansion by defeating the last great Indian rebellion. Colonel Bouquet defeated Pontiac's forces in the Battle of Bushy Run just to the east of the forks.

In the 1768 Treaty of Fort Stanwix, the descendants of William Penn purchased from the Six Nations western lands that included most of the present site of Pittsburgh. In 1769, a survey was made of the land situated between the two rivers, called the...