Surrounding this square, that used to be the place of a fish market, are the southern flank of the Cathedral transept, dating back to 1343, the rear of the Baptistry, begun in 1167, and the Bishops Palace, built by will of Bishop Omobono Offredi Ambrosini in 1793 and completed in early 19th century. 
From the square you can also admire the so-called “holy field” of the canons. From here it is possible to reach on request, underground, a wonderful mosaic which dates from around the 11th or 12th century.

Ph. Salvo Liuzzi Photo