The Basilica was open for most of the night, shutting its doors for only three hours between 2.30am and 5.30am on Friday.
The body of the 88-year-old pontiff, who died on Monday in his rooms at the Vatican's Santa Marta guesthouse after suffering a stroke, was brought to St Peter's in a solemn procession on Wednesday.
Since then, almost 130,000 people from all over the world had bid farewell to the pontiff, the Vatican said.
"What surprised me was how determined he was to serve the church and love his people with all his energy, to the very end," Italian Cardinal Giovanni Battista Re - the ceremonial leader of the College of Cardinals and a retired Vatican official- told Italian daily la Repubblica in an interview published on Friday.
A conclave to choose a new pontiff is unlikely to start before May 6.
In the meantime, cardinals present in Rome who have assumed temporary control of the 1.4 billion-member Roman Catholic Church are meeting daily, in a so-called general congregation.
On Friday evening, at the end of his lying in state in the basilica, Francis's coffin will be closed privately in the presence of a few aides.
The city is bracing for the arrival of hundreds of high-profile delegations attending the funeral on Saturday, including US President Donald Trump, who will be flying into Rome late on Friday.
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