Two New York City famous pizza parlors opened in Center City Philadelphia about the same time.  Both use coal ovens which burn extra hot and produce a great crust.

Of the two, Pietro's has a broader menu, a lot more than pizza.  But pizza is the thing to order.

That's a tomato pie above, and very unique arugula pie upper right, and sausage pie to the left.

Pietro's has outdoor seating on Walnut Street in season.  A nice way to spend an afternoon.

But pie vs. pie, I'm a fan of the other NY pizza parlor, Lombardi's.