Like his predecessor 500 years ago, Pope Benedict late yesterday led  prayers at the Sistine Chapel in celebration of the Vatican chapel's famed frescoes.

On October 31, 1512, only 20 years after the discovery of America, Pope Julius II said an evening vespers service to inaugurate the room where Michelangelo toiled for four years, much of it on his back, to finish his ceiling frescoes. The frescoes immediately became the talk of the town and have since become the talk of the world.

The anniversary came as the Vatican warned it may eventually limit visitors to protect one of the wonders of Western civilisation.

The Sistine Chapel is arguably the most visited room in the world. With mass tourism growing, every year some five million people, as many as 20,000 a day in summer, enter the chapel and crane their necks upwards.

The ceiling of the chapel, where cardinals meet in secret conclaves to elect new the pope, includes one of the most famous scenes in the history of art - the arm of a gentle bearded God reaching out to give life to Adam in the creation panel.