 An ancient and unusual privilege of the Duomo is its right to employ ceremonial armed guards, rather on the line of the Papal Swiss Guard at the Vatican.Known as "Alabardieri" from the halberds they carry, the date of their institution is described in a 1763 edict of Maria Theresa of Austria as ‘immemorial’.Their eighteenth-century style uniform, of blue wool with gold braiding and a belt buckle with an image of the Iron Crown, is unchanged from that approved in the edict, except that since the Napoleonic period the bicorne hat has replaced the earlier tricorne.