I left from the Youth Hostel on the north end of Rome and cycled 103km to Montefiascone at the southern end of Lago di Bolsena.  I spent the night at a Campeggio Amalasunta below Montefiascone (a classic hill town).

Here's a Google Map overlay of the route from Rome to Lago De Bracciano (the first 40km of the route: map