If you like GREEK pizza - which I find hard to describe, but you know it when you taste it - try Old City Pizza, I believe on the corner of 3rd and Arch. It is the only edible Greek pizza I have found in the Phila. environs. (Any other suggestions?) (The other great Greek pizza is in Towson Maryland - Pizza Palace which is just a take-out now since that dive burned down in about 1987.)
It's a great pizza shop, a few tourists (Independence Hall and all), but not too many given its look which is nothing notable. They renovated the interior recently - fortunately you don't sink through torn up booth seats anymore. Unfortunately, they got rid of the bicentenial era patriotic wall paper.
We always get the mushroom pizza. I have tried the Greek salad which is ok.
Please give it a try to keep the high priced stores and restaurants in Old City at bay.