The Baldacchino by Bernini (1633)

Summary:

• The Basilica centers around the Papal Altar where only the Pope celebrates Mass. It was consecrated by Clement VIII, June 5, 1594.  
• A baldacchino is a processional altar.
• This baldacchino was designed by Bernini, commissioned by Pope Urban VIII & St. Peter's tomb is below the altar.
• Bernini's baldacchino is emblematic baroque design made of cast bronze and partially gilt.
• It took 9 years to build from 1624 to 1633.
• The entire project required more than 100,000 pounds of bronze, much of which was stripped from the Pantheon.
• The bronze "drapery" features the heraldic bees (symbol of chastity) of the Barberini family to whose family Pope Urban VIII belonged (he commissioned the baldacchino). 
• Inside the "ciborium" is a dove, the symbol of the Holy Spirit, in a burst of golden rays, which complements the design of the Holy Spirit Window behind the baldacchino, above the altar.
• Above the frieze on each capital, four angels, (work of Francois du Duquesnoy) offer garlands.
• The vertex, where four ribs and palm branches converge, is crowned by the cross, set on a golden globe.
• The twisted columns are 20m tall and are presumably modeled after the eight columns of Solomon's temple, but the spiraling twists also suggest movement upward.
• The baldacchino is supported by 4 large (2.68m) marble pedestals . Each of the outer sides of the pedestals are decorated with Urban VIII's family coat of arms, the Barberini bees, and shields representing the stages of a woman in childbirth.  It begins on the Southeast corner and moves clockwise, ending with a baby's face on the Northeast corner. 
• The four columns are decorated with sprigs of olive, bay and cherubs (putti); acanthus leaves adorn the capitals.
• Eight putti carry the keys and the tiara of St. Peter, as well as the sword and book of St. Paul. 
• The canopy was revealed to the public on St. Peter's day in 1633.
• The artist and those who commissioned the work were criticized because of the "cost no object budget" and enormous quantity of bronze used (103,229 lbs, taken from the Pantheon and other sites).  
• To compensate for the loss of the Pantheon's treasures, two bell towers were built on either side of it which the public called the "donkey ears of Bernini." They were later demolished in 1883.
• The statement of the time was, "what the barbarians did not do, the Barberini's did."

For more indepth info see:   http://stpetersbasilica.info/Altars/PapalAltar/PapalAltar.htm