The majestic, massive cathedral was built in the Italian Gothic style. Its construction was initiated by Pope Urban IV and lasted three centuries - from the fourteenth to the sixteenth century. From the outside, the attention is drawn to a large rosette window, gilded mosaics decorating the facade and three pairs of large bronze doors covered with bas-reliefs.
The cathedral consists of a nave and two aisles. They are separated by rows of cylindrical columns of travertine and basalt. You can also see a large stained glass window made in the first half of the 14th century by Giovanni di Bonino, a glass master from Assisi.
There are two chapels in the temple, the walls of which are decorated with antique frescoes depicting scenes from the Day of the Last Judgment. A reliquary with a corporal with blood stains is kept in the temple. According to tradition, a miracle took place in the nearby town of Bolsena - during the mass the Host began to bleed so badly that it stained the fabric on the altar. This was to prove the miracle of transubstantiation.