This is the original Primanti Brothers though not my favorite. It is the best one to see a wide variety of Pittsburghers eating lunch. Last time I was there, I sat at the bar surrounded by general contractors and guys in suits. It's a nice bar and a surprisingly large area for eating inside. The sandwiches come quick and cheap as is to be expected.
The wonder of a Primanti Brothers sandwich hinges on the great white bread, vinegary coleslaw, and hand-cut fries stacked high.
I recommend the sweet sausage sandwich - though it's definitely one of the messiest.