RE: Philadelphia/Center City
Try going out on Saturday to Mama's Pizzaria on Belmont Avenue in Bala Cynwyd... right across the boro line - City Line Avenue - from Philadelphia. You might want to call for hours and directions. My authority tells me that it is Not To Be Missed... the best cheese steaks and hoagies in the city.
Secondhandly, Ort. Carlton in Athens, Georgia.
P. S. Both Pat's and Geno's are decent (I've tried them!), but I gather that there are dozens of better places about. Happy hunting!