The museum was reopened in 2013 after a long period of renovations. The collection gathers the Tesoro del Duomo (Duomo Treasure) and works of art form the Catheral and its many constructions sites. The items in the collection are presented in chronological order, following the construction phases of the Cathedral, from its foundation, in 1386, to the XX century.
The many masterpieces gathered in the collection include the Modellone Ligneo (wood model) of the Cathedral, the amazing marble sculptures sculpted by Candoglia, the bright windows, the original iron frame of the Madonnina and the winning sketches of the contest of 1950 for the fifth door of the Duomo, drawn by Lucio Fontana and Luciano Minguzzi.