Michelangelo's Sistine Chapel ceiling frescoes turned 500 on Wednesday with the Vatican warning it may eventually limit visitors to protect one of the wonders of Western civilization.
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 problem is that it sometimes feels that they have become the walk of the world. 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. Most are left awestruck.
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.
Earlier this month, Italian literary critic Pietro Citati sparked a storm by writing an open letter in a major Italian newspaper denouncing the behavior of crowds visiting what is technically a sacred place.
Tourists, he said, "resemble drunken herds" as they unwittingly risked damaging the frescoes with their breath, their perspiration, the dust on their shoes and their body heat.