With the recent gloomy weather giving way to sparkling sunshine and an azure sky, an even higher authority than the pontiff appeared to have given his blessing to the celebrations to mark the 78th birthday of Francis, formerly Jose Bergaglio.
The dancers, from all over Italy and further afield, were among 13,000 people at St Peter's for the Pope's weekly public audience.
Non-dancing well-wishers came bearing gifts including a birthday cake and mate, a traditional Argentinian drink, before listening to the leader of the world's Catholics issue a solemn condemnation of recent terrorist atrocities in Pakistan, Yemen and Australia.
Around midday, the dancing started. "Happy Birthday, Pope Francis! Let's widen out this circle," shouted Cristina Carmorani, a dance teacher from Conventello, near Ravenna in northeastern Italy.
It was Carmorani who came up with the idea for the birthday tango and launched an appeal for couples to come and do it though her "Tango for Francis" Facebook initiative.
More than 3,200 people had signed up to take part, she had said, with most of the volunteers elderly couples.
'I Love it'
The Pope revealed his passion for the beguiling tunes to which the dance is performed in an interview several years before he became pontiff.
"I love it. It is stronger than me," he said. His younger sister has also been quoted as saying that the pontiff, a keen sportsman in his youth, was also a very accomplished dancer.
Last year, on the first anniversary of his election as Pope, Radio Vatican marked the occasion by playing several of his favourite tango tunes, including the famous "Por una Cabeza" ("By a head") by Carlos Gardel.
The papal birthday was celebrated in a very different style by the "Papaboys", an association of young Catholics who had organised a prayer marathon at the San Lorenzo hostel for pilgrims visiting Rome.
After a midnight mass, the devout group prayed continuously until it was time for the papal audience and subsequently returned to continue in the same vein through an entire 24-hour cycle.
Spanish poultry farmers sent 800 kilogrammes (1,750 pounds) of chicken to be distributed by the Vatican's charity services via soup kitchens for the homeless around the Catholic headquarters.
The Vatican press office, which stressed that the tango was not an officially sanctioned event, said there would be a surprise for the poor later in the day, without releasing any further details.
Watch a video of the tango celebration: