Cardinals celebrate Mass before entering conclave on March 12; 2013 in St Peter's Basilica; Vatican ahead of a conclave to elect a new leader for the Catholic world. - Center: The Baldachin (baldaquin) by Gian Lorenzo Bernini (1598-1680)Bernini's first work at St. Peter's was to design the baldacchino; a pavilion-like structure 28.74 metres tall and claimed to be the largest piece of bronze in the world; which stands beneath the dome and above the altar.(Saint Peter's basilica; basilique Saint-Pierre; Petersdom)Vatican 2013