From Roma Termini train to Rome airport, fly to Belgrade airport, then bus to Belgrade. 4hrs 55min 107 €. From Roma Termini train to Bologna Centrale, train to Tarvisio Boscoverde, train to Villach Hbf, then train to Beograd. 19hrs 44min 151 €. From Cavour Metro to Rome, bus to Florence, then bus to Belgrade. 22hrs 05min 115 €. From Roma bus to Zagreb then bus to Belgrade. 24hrs 33min 124 €. From Rome drive to Belgrade. 12hrs 42min 227 €.