Among the vestments conserved in the Museum there are several copes wide, semicircular robes used like capes, open in front and held with a clasp, chausubles the robe used during the celebration of the mass in different colors according to the liturgical season; stoles or strips of linen, silk or wool embroidered and decorated worn by the celebrant, maniples strips of narrow, short textile worn on the left arm.
The room dedicated to the liturgical vestments contains chausubles of various bishops of Viterbo; Sermattei (1719-1731), Degli Abbati (1731-1748), Simonetti (1748-49), Oddi (1750-70), Ridolfini (1803-06), Pianetti (1826-60) and Grasselli (1899-1913) besides the embroidered chausuble a gift from Pope Pius IX to Capitol of San Lorenzo Cathedral.
In the room dedicated to Mons. Salvatore Del Ciuco there is also a stole, a tiara with the symbol of St. Peter and other objects that belonged to Mons. G.L. Bentivoglio the Archbishop of Catania (1899-1978) originally from Viterbo. On the walls are the portraits of the bishops of the Viterbo Diocese.