The cathedral is dedicated to the patron saint of Montefiascone and has one of the largest domes in Italy, 27 meters in diameter. It is recognizable from almost all parts of Tuscia. The cathedral was built between the 1400 and 1500 on two levels: the lower church with the relics of Saint Lucia Filippini and the upper church. The construction of the dome is from 1670 after a fire had destroyed the roof of the cathedral and part of its interior. The 'ribbed' dome with obvious grooves characterizes the landscape of the country in a decisive manner and dominates the simple bell towers and simple facade.