The Museo del Capitolo di San Lorenzo is located in Piazza IV Novembre, Perugia’s main square, right in front of the Fontana Maggiore and next to the entrance of the Cathedral. This museum was reopened in 2000, after significant interventions of restoration had noticeably widened its exhibition space. Instituted in 1923, the Museum collection consists of works coming from the Cathedral and the churches of the Diocese, such as: goldsmiths, liturgical vestments and fittings, paintings and sculptures testifying the artistic production from the 11th to the 19th century. In the Lapidarium, held in the recently restored underground halls, probably part of what once was the Palace of Martino IV, numerous archaeological pieces are displayed. The exhibited fragments, which date from the 13th to the 16th century, come from the ancient cathedral and the worship edifices around it. The rich Art Gallery it possesses is second in Perugia, for the number of works conserved, only to the National Gallery of Umbria
. The works worth signaling are: St Onofrius Altarpiece painted by Luca Signorelli for the Cathedral in 1484, which is the sole work of the painter—who was born in Cortona—for the town of Perugia, the Deacon Head sculpted by Arnolfo di Cambio, the architectonic fragment attributed to Giovanni Pisano’s workshop, the two Triptychs of Meo da Siena and Agnolo Gaddi, the Pieta of Bartolomeo Caporali and the Marriage of the Virgin of Carlo Labruzzi, painted in 1815 to substitute the painting on St Joseph Altar by Perugino that was requisitioned by the Napoleonic troops in 1797. Guided Visits right below the Cathedral have led visitors to the discovery of an underground archaeological pathway—for a length of at least one Kilometer—since January 2011. In fact the Cathedral was built on top of the Etruscan town terracing. The Guided Visits allow the visitor to observe the several layers defining the different epochs of the town: Etruscan, Roman, Late Antiquity and Medieval. The excavations have brought to light the majestic retaining wall of the terrace, built with a technique that is similar to that of the Etruscan Walls, but better preserved. The presence of worship sites in the area, dating back to the archaic period—6th-4th century B.C.—is testified by the presence of the remnants of the foundation of their structures and by the polychrome terracotta decorations of the temples—the Silenus head sculpted antefixes—exhibited in the National Archaeological Museum of Perugia today. At the foot of the terracing, a stretch of road of “basolato”—i.e. made of slabs of black lava stones—part of an important route axis of the Etruscan-Roman Town reconnects with the part found a long time ago under Piazza Cavallotti. Probably starting in byzantine times, the terracing was exploited for defensive purposes, and progressively—during the 10th century—around the Cathedral, a series of monumental buildings, towers and palaces started to be raised, the “Castle of San Lorenzo”, as it was called in the medieval documents.