From Roma Termini train to Rome airport, fly to Belgrade airport, then bus to Belgrade. 4hrs 55min 106 €. From Roma Termini train to Bologna Centrale, train to Tarvisio Boscoverde, train to Villach Hbf, then train to Beograd. 20hrs 15min 232 €. From Cavour Metro to Rome, bus to Florence, then bus to Belgrade. 22hrs 03min 106 €. From Roma bus to Zagreb then Bus to Belgrade. 24hrs 33min 122 €. From Rome drive to Belgrade. 12hrs 42min 224 €.