Entering through the central portal on the façade, you are greeted by two ancient Romanesque holy water fonts depicting a lion and a lioness, which were part of the original church.
In front of you stand three naves, which in the center reach a length of no less than 87 meters, marked by two rows of five pilasters. The average width of the cathedral is 36 meters, but in the transept area it widens to 56 meters.
If you look up above the portal you have just walked through, you can admire the splendid polychrome designs of the stained-glass windows that make up the façade's rose window: they date back to 1488.
Past the holy water fonts, a little further on, to your left is a splendid late-16th-century Renaissance-style temple with polychrome marble columns enclosing a precious 15th-century baptismal font with a finely carved wooden lid.
Along the aisles you can admire statues, stuccoes, and paintings of exquisite workmanship, and even wool and silk tapestries made between 1525 and 1635, from the most important manufacturers of the time in Milan, Ferrara, Florence and Brussels.
Now pause and restart when you are near the central altar.
In the center you can admire the very old Romanesque marble altar from 1317, inside which are preserved the relics of Saints Protus, Hyacinth, Liberata and Faustina.
In the side apses, on the other hand, there are two imposing chapels.
On the right is the Chapel of the Assumption, where there is a wonderful Baroque altar completed in 1686, while on the left is the Chapel of the Crucifix, whose altar was completed in 1674.
Get close to the wooden crucifix in the latter chapel, made in the late 15th and early 16th century, and carefully observe the head of Jesus. You should note that what you see is real human hair!
Interesting fact: walking down the aisles, you will not have missed the two imposing organs located at the sides. There are two others a little more hidden: one above the left sacristy and one behind the altar of the Crucifix. Just think that, in total, the four organs have as many as 6515 pipes with 69 different sound registers! Imagine how wonderful it would be to hear them during solemn celebrations!
