Michelangelo took four years to paint the Sistine Chapel's 1,100 square-metre vault, a labour he completed on 31 October 1512 - All Saints Day - when Pope Julius II celebrated Vespers to mark the event.
The Sistine Chapel's walls were decorated by a number of Renaissance arts including Sandro Botticelli. In addition to the ceiling, Michelangelo was employed to decorate the wall behind the altar. He did so by completing the apocalyptic "Last Judgement" in 1541.
Papal conclaves take place in the Sistine Chapel, where the most recent restoration of the frescos was completed in 1994 and took 14 years.
Vatican Museums director Antonio Paolucci in September warned that dust and pollution in the Sistine Chapel, which is visited by millions of tourists annually, posed a threat to the frescos.