On one side of the church's facade, near the door of the old praetorian guard, are crosses carved in to the shape of the Tau. Historians believe this may be evidence of an underground Templar society that is rumoured to have existed in Castel del Piano centuries ago.
Inside there are no more references to the Templars, but there is a beautifully carved wood and polycrome painted 17th century statue of the Madonna di Loretto. In 1634, Castel del Piano's devoted residents carried this statue on a pilgrimage to Loretto as a show of their devotion.
To the right of the altar of Santa Croce and San Desiderio is a painting known as 'Verifica della Vera Croce' by Francesco Nasini, while on the other altar is the 'Miracolo di Bolsena' by Gioacchino Sorbello, as well as a traventine font. All three of these works are modest, but still stiking to behold.