There was a Primanti Brothers restaurant next door to my hotel. Many years ago, there was only one Primanti Bros. restaurant.
It was in the strip districts (warehouses and wharfs)and it was open all night because the trucking and trains and barges ran 24/7.
We would go out dancing at clubs and then go to Primanti's at 2 a.m. for a sandwich.
After all that dancing, it really hit the spot. :) Now they are a chain. But don't have the characters and atmosphere of the original.

The Steel City’s Signature Sandwich
"Steak, cheese, egg, fries, coleslaw, tomatoes, and bread. Separately these items may not seem too intriguing, but when combined,
they create a mountain of taste. In "The Steel City," the people are known all over as tough, gritty, blue-collared
factory workers who bleed black and gold for the Steelers, drink Iron City beer, and sing along to hometown hero Donnie Iris in their distinct dialect.
One more thing that stands out to anyone who has been to "The City of Bridges" is the famous Primanti Brothers sandwich,
a must-eat experience for anyone near Pittsburgh. These remarkable sandwiches have been filling the stomachs of Pittsburghers for over 75 years."
http://pabook2.libraries.psu.edu/palitmap/Primantis.html