Pittsburgh is the second-largest city in the U.S. state of Pennsylvania. Pittsburgh is known as both "the Steel City" for its more than 300steel-related businesses, as well as "the City of Bridges" for its 446 bridges. The city features 30 skyscrapers, 2 inclines, apre-revolutionary fortification and the source of the Ohio River at the confluence of the Monongahela and Allegheny Rivers. Nine Fortune 500 companies calling the area home ranks Pittsburgh for eighth most Fortune 500 headquarters in the nation. Area retail is anchored by over 35 shopping malls and a healthy downtown retail sector as well as boutique shops along Walnut Street, in Squirrel Hill and Station Square. High-end fashion can always be found at Ross Park Mall with over 150 retailers .