This is one of the oldest churches in Milan and one of most historically interesting medieval buildings in Lombardy. It was begun in 379, and was a small three-aisled, transept-less church. In 386 it was consecrated by St. Ambrose who, when he died in 397, was buried beside the bodies of St. Gervase and St. Protasius inside the Church. In 739 the monastery of the Benedictine Monks was built next to the church and in the 9^th century the simple right bell-tower, known as the bell-tower of the monks, was erected. The apse and the presbytery were constructed in the 10^th century, while in the 12^th century, the aisles, the drum, the entrance and the left bell-tower, known as bell-tower of the canons (in Lombard Romanesque style with pilaster strips and friezes of little hanging arches) were built. It was finished in 1889 with the completion of the three-arched loggia. At the end of the 15^th century, Cardinal Ascanio Sforza gave the task of constructing the cloisters and the portico of the rectory to Bramante. In the following centuries other changes was made, but in 1857 the archduke Maximilian of Austria ordered that the baroque additions to the church be removed. It was damaged in the august 1943 bombings, and restored by the architect Ferdinando Reggiori. The atrium in the form of rectangular portico, replaces the one in front of the church, built by the Archbishop Ansperto who governed the Milanese clergy from 868 to 881. It was given its present form in the first half of the 12^th century. The capitals of the pillars in the robust portico are sculpted with flora, symbolic animals and monstrous figures. On the walls, plaques from tombs, bas-reliefs and the sarcophagus of Archbishop Ansperto. The façade, flanked on either side by the two bell-towers, is composed of two super-imposed loggias. The top one has a central arch flanked by four diminishing sized arches and below is the narthex or atrium with its three portals. The great architraves of the two-side portal are decorated with medieval bestiary-inspired carvings. The central door lunette and architrave are carved with 8^th and 10^th century wicker patterns and monstrous creatures. The original carved wooden door with scenes from the Life of David and Saul date from the 4^th and 7^th centuries; the fragments are kept in the museum of the Basilica. The two sides of the door in bronze are of the 11^th-12^th century. To the left of the portal, marble Sepulchre of Pier Candido Decembrio, a humanist (d. 1477) by Tommaso Cazzaniga.