The Basilica has 6 bells, placed in the room under the Roman clock, only 3 of them are visible from ground level while the rest are hidden behind the bourdon. They range from the smallest which is 260 kg to the massive bourdon that approximately weighs 9 tonnes. From 1931, the bells are operated electrically, thus permitting even the largest bell to be tolled from a distance. The oldest bell Rota dates from 1288 and the bourdon called Campanone is rung at Christmas and Easter, on the Solemnity o