“Pittsburgh, at the junction of the Monongahela and Alleghany Rivers, is the second city in the State. It has a large trade and is noted for its commerce and its vast manufactures of iron. Alleghany City and Birmingham are connected with Pittsburgh by bridges.”
From A System of Modern Geography. The engraving may not be accurate down to the individual buildings, but it probably does a good job of conveying the general impression produced by the city just after the Civil War.