Five centuries after Michelangelo's ceiling of frescoes was inaugurated in the Sistine Chapel, Pope Benedict XVI on Wednesday celebrated the "symphony of figures" contemplated during prayer.

Benedict marked the anniversary by saying vespers beneath the frescoes, as his predecessor Julius II had half a millennium earlier.

The pope said that contemplating the frescoes in the chapel of the Apostolic Palace renders them "more beautiful still, more authentic. They reveal all of their beauty."

"It is as if during the liturgy, all of this symphony of figures come to life, certainly in a spiritual sense, but inseparably also aesthetically," the pope said.

At least 10,000 people visit the site each day, raising concerns about temperature, dust and humidity affecting the famed art. But a Vatican Museums official says there are no plans to try to limit tourists' access.

Museums Director Antonio Paolucci said in an article in the Vatican newspaper on Wednesday that sometimes as many as 20,000 people a day visit the chapel. But, he said, for the time being "the adoption of a maximum number (of visitors) will not be necessary."