Basic pizza place in downtown Pittsburgh. The prices are very reasonable - each cut, thick or thin, is $1.85, with toppings at 30 cents per topping. I ordered two cuts of the thick Sicilian square pizza, which were quite good. The crust was airy on top and very crispy on bottom. They also have fountain drinks (refills are 25 cents), or you can order bottled drinks from a vending machine.
The wait staff was friendly, and the food comes out relatively quickly. They have plenty of seating, including a dining room upstairs. I highly recommend Mamma Lucia if you want quick basic and Italian food/pizza at very reasonable prices.