At the doors of Viterbo, follow a diviation and visit the ruins of Ponte Camillario, an ancient Roman handiwork.
A bit futher there is a wonderful surprise: an Etruscan catacomb. You can visit it bearing a torch. What remains is to go up and down continuosly among fields and woods, made hard by water shortage and few road-houses. At the doors of Vetralla, you can visit the ruins of the Pieve of S. Maria di Forcassi.