The entrance to the Cathedral of St Mary of the Assumption and St Justina is in the Piazza del Duomo, just in front. The cathedral was built on the orders of Pope Paul III Farnese, who was determined to embellish the city before the duchy was handed to his son Pier Luigi. (Yes, in the 1500s popes could have children.) The column in the centre of the square was also owned by Farnese. The cathedral, Romanesque with Gothic elements, had been erected well before the square took its current form, between 1122 and 1233 to be precise. A century later came the bell tower, which is a real highlight of the building, along the right side of the façade, while the remarkable frescoes on the high ceiling date from the 1600s. The most notable frescoes can be seen in the nave and dome, with eight segments started by Pier Francesco Mazzucchelli ("Il Morazzone") and completed by Giovanni Francesco Barbieri ("Il Guercino"). It was Barbieri who painted the six segments depicting the prophets and also the lunettes, which portray scenes from the life of the infant Jesus, alternating with eight fascinating Sibyls. Both prophets and sibyls can be admired up close by following the medieval pathways inside the dome, accessible from the garden behind the church.
In the presbytery, look for the wooden polyptych of the Majesty, carved and painted, and the choir, both dating from the fifteenth century. After admiring the sculptures on the pulpit, which you might not think were a skilful neo-Romanesque addition from the early 20th century, you descend into the cavernous crypt. It has 108 columns and is the resting place of St Justina, to whom the is dedicated, together with St Mary of the Assumption.