Located in the middle of the walled town, the church was built between the 11th to the end of the 13th century and was possibly the first cathedral in Como. It features a complex planimetry including three short naves, provided with women's galleries. The naves then broaden - around the tyburium - making up a wide body with three choirs flanked by an ambulatory: particularly refinded is the central apse with a series of niches at the base, an inner loggia and a smaller outer loggia. Outside next to the apse there is a remarkable sculpted portla featuring Daniel in the lion's den; inside there are paintings dating back to the 14th century, frescoes of the early 17th century and piantings by Carlo Innocenzo Carloni. The facade and the bell tower were restored in the early 20th century.