The Vatican said on Wednesday that it may one day have to limit entrance to the Sistine Chapel if dust and other pollutants brought in by visitors threaten to take a toll on the Renaissance treasure.
Here is a brief sketch of the Sistine chapel
* The Sistine Chapel was commissioned by Pope Sixtus IV, from whom it derives its name, in 1475. It was designed to be - and still is - where Catholic cardinals hold conclaves to elect a new pope and was first used for that purpose after the death of Sixtus in 1484.
* Michelangelo painted most of the chapel in two periods between 1508 and 1541. It is now part of the Vatican Museums and is open to the public when it is not being used by the pope. Michelangelo painted the ceiling between 1508 and 1512 and the Last Judgement panel between 1535 and 1541. It is one of the world's most famous treasures of Renaissance art. Wednesday is the 500th anniversary of the inauguration of the ceiling frescoes in 1512.
* Michelangelo was accused of immorality and obscenity for depicting naked figures in a church. After his death, Church officials ordered another artist to paint loincloths over the offending genitalia.
* The side walls were decorated by other artists, including Pietro Perugino, Sandro Botticelli and Domenico Ghirlandaio.
* In 1994 Pope John Paul opened the restored Sistine Chapel after frescoes were returned to their original splendour by a 14-year cleaning project. At the time, some critics said the frescoes were damaged. But most agreed that the project had brought life back to the colours, which had been dimmed by centuries of candle and incense smoke, grime, and previous botched restorations.