According to chronicles, the Duomo was built in the place that Theodolinda supposedly dedicated an oratory to St. John in the 4th century. It was constructed in Gothic style during the 13th and 14th centuries and the first stone was laid on 31 May 1300.
Divided into 3 naves by octagonal pillars topped by medieval capitals, the cathedral has a transept and flat apse. The side chapels were added during the 14th c. and the large choir installed by demolition of the apse.
In the same period, the facade was completed under the guidance of Matteo da Campione but unfortunately only a few sections of his work are visible following restoration work from 1889-1908 by Luca Beltrami.
The decorations of the interior and 13th century. frescoes were substituted during the 17th c. with a pictorial cycle that represented an anthology of 17th-18th c. painting in Lombardy.
15th c. frescoes can be seen in Theodolinda's chapel to the left of the apse and in the presbytery. The Duomo holds the Treasure of Monza, including the Iron Crown and works of art from the 4th and 5th centuries.
Milan