The Sistine Chapel has been closed to visitors as work got under way to prepare it for the conclave, where cardinals from around the world will gather to elect the new pope.
The Vatican said that it was waiting for five more cardinals to arrive before setting the date for the election.
Michelangelo's frescoed masterpiece closed at 1pm to visitors, one of the first visible signs that the election was nearing. Construction work involves installing a false floor as well as installing the stove where the ballots will be burned.
A total of 110 of the 115 voting-age cardinals attended the second day of preparatory meetings to organise the conclave, discuss the problems of the church and get to know one another.
Those heading to Rome included: Egyptian Patriarch Antonios Naguib, and Cardinals Karl Lehmann of Germany, Jean-Baptiste Pham of Vietnam, Kazimierz Nycz of Poland and John Tong Hon of Hong Kong, the Vatican said.
Vatican spokesman the Rev. Federico Lombardi said they were expected in the coming days and that there was no concern about the delay; some had important meetings of bishops to attend.
During the second day of pre-conclave meetings, cardinals asked for information about the management of the Vatican bureaucracy - and managers responded - after cardinals said they wanted to get to the bottom of allegations of corruption and cronyism in the Holy See's governance.
They also agreed on a telegram sent to Benedict XVI thanking him for his "brilliant" ministry and his "untiring work in the vineyard of the Lord."
And the Vatican showed off the urns into which the cardinals will place their ballots, the same silver and bronze flying-saucer-like urns used in the 2005 conclave that elected Cardinal Joseph Ratzinger pope.