Unnecessary pinnacles and turrets were prohibited.
The most magnificent part of the exterior and indeed the finest polychrome monument in existence is the west façade, built of richlysculptured marble from the designs of Lorenzo Maitani of Siena, and divided into three gables with intervening pinnacles, closely resembling the front of Siena cathedral, of which it is a reproduction, with some improvements.
The cuneiform inscriptions are on the rock pinnacles above the town, with some rock chambers, indicating a town or fortress of the Vannic period.
The sides of these ridges and pinnacles are bare of vegetation and display a variety of colours in buff, cream, pale green, grey and flesh.
The finest part of the exterior is the choir, which is ornamented with a profusion of carved pinnacles and balustrading.