By train from Rome Termini, take the FR3 regional line towards Viterbo and change at Capranica-Sutri; the total journey is around 70 minutes. Trains run roughly hourly. From Capranica-Sutri station a taxi or infrequent local bus covers the remaining few kilometres to Civita Castellana. Check current timetables before travelling, as the connection is not always well-timed.
By car the most direct route is the Via Flaminia (SS3), which runs directly from Rome through Civita Castellana towards Foligno. The drive from central Rome is about 65km and takes around an hour in normal traffic — less on a Sunday morning. The road passes through some attractive Tiber valley scenery north of Rignano Flaminio. From Viterbo, Civita Castellana is about 30km south on the SS2 and then local roads, under half an hour.