Arezzo Cathedral is perhaps one of the largest buildings in the old city.  Perhaps it is not as ornate as the Public Library or some other churches here  but it is quite impressive.  Inside there are some beautiful fresco covering the entrée ceiling of the cathedral as well as a couple burial monuments dedicated to old Popes dating back to 1267, there are other relics and monuments dating back to the 4 century AD. There are even original artworks by Donatello himself who was one of the many famous Italian artists.  It is an impressive building with a massive staircase leading up to it, just like the main cathedral in Sienna.