The Basilica of Saint Ambrose, the patron saint of the city, is one of the oldest churches in Milan. The Christian basilica was founded in the 4th century AD by the bishop of Milan Ambrose, who is buried here, and after whom the church is named. In the 9th century the church underwent major renovations under the watchful eye of the bishop Angilberto II (824-860). The great apse was decorated with a large mosaic, still there today, portraying Christ with saints Protasio and Gervasio accompanied by the archangels Michele and Gabriele. The mosaic portrays two episodes of St Ambrose’s life.
The Basilica of Saint Ambrose was placed under the ciborium. Made by Vuolvino this is one of the most famous masterpieces of Carolingian art in the period between 824 AD and 859 AD with an impressive list of materials including gold, silver, precious stones and enamels. The altar was designed to display the relics of Saint Ambrose, which are visible through a window on the rear side.
The basilica assumed its current appearance in the 12th Century when it was rebuilt following patterns of Romanesque architecture. The reconstruction of the church coincided with the full affirmation of the city of Milan when the original edifice was maintained; also included were the three aisles with apses, a portico with elegant arches supported by semi-columns and pilasters preceding the entrance.
The flat appearance of the hut-like façade is typical of Lombard medieval architecture. It has two loggias, the lower one with three arches of equal dimensions joining the portico. The upper loggia has five arches of different height that follow the ceiling. Today, the Basilica of Saint Ambrose stands as an isolated example of Lombard Romanesque style, while other contemporary examples (such as cathedral of Pavia, Novara and Vercelli) have since been destroyed or radically transformed.
The basilica has two bell towers. The right one, called dei Monaci (“of the Monks”), is from the 9th century and has a severe appearance. The left and taller of the two bell towers dates to 1144 AD, with the last two floors added in 1889 AD. The current crypt was built in the second half of the 10th century while the lantern was added toward the end of the 12th century. The lantern collapsed soon afterwards (July 6, 1196 AD) but it was immediately rebuilt.