Viterbo sits at the centre of Tuscia — the old Etruscan heartland — and the surrounding countryside is full of places worth a half-day or full-day excursion.
Lake Bolsena, 30 km north, is the largest volcanic lake in Europe, ringed by medieval villages and with remarkably clear water. The town of Bolsena itself is pleasant, with a well-preserved castle and the Basilica of Santa Cristina, site of an important Eucharistic miracle in 1263 that inspired the Feast of Corpus Christi.
Tarquinia is the greatest Etruscan site in Lazio, about 45 km southwest. The Necropolis of Tarquinia, a UNESCO World Heritage Site, contains painted tomb chambers from the 7th to 2nd centuries BC — some of the finest Etruscan painting to survive anywhere.
Lake Vico, immediately south of Viterbo, is the smallest and most intimate of the volcanic lakes in northern Lazio, enclosed within a nature reserve. The crater rim makes for good walking and the surrounding beech and chestnut woods are beautiful in autumn.
Civitavecchia, an hour west, is the main port for ferries to Sardinia and is worth visiting for its impressive Michelangelo-designed fortress and the Roman imperial baths.
