American and United Airlines have a $499 round trip fare deal from Philadelphia to Rome for departures mid-March to May 10. AA offers nonstop flights. United is train service from PHL to EWR, then nonstop to Rome. The advantage of United Airlines are low fare departures December to March from $520 to $554 round trip.
United Airlines Philadelphia ZVF Rail Station – Newark EWR – Rome FCO – EWR – ZVF
American Airlines Philadelphia PHL – Rome FCO – PHL Nonstop