a pavilion-like structure 30 metres (98 ft) tall and claimed to be the largest piece of bronze in the world, which stands beneath the dome and above the altar.it is the burial site of its namesake Saint Peter, who was one of the twelve apostles of Jesus
Basilica di San Pietro in Vaticano - May 16, 2008
source: http://en.wikipedia.org/wiki/St._Peter's_Basilica
