Pope Francis, Latin American's first pontiff, visited a Rome basilica on Thursday at the start of a papacy looking to bring the Catholic Church closer to ordinary people.
The 76-year-old former archbishop of Buenos Aires and railway man's son, Jorge Mario Bergoglio, prayed at Rome's Santa Maria Maggiore basilica to kick off his first full day as the head of the world's 1.2 billion Catholics.
"The election of a pope from the 'new world' is an occasion of genuinely historic proportions," said Australian Prime Minister Julia Gillard.
"Revolution at St Peter's" headlined the Italian daily La Repubblica, saying Francis's election represented "geographic and cultural upheaval" for the Vatican.
The newly minted pontiff emerged smiling onto the balcony of St Peter's Basilica on Wednesday to cries of "Long live the pope!" from tens of thousands of pilgrims massed in the famous piazza.
The first non-European pope in nearly 1,300 years devoted his first prayer to his predecessor Benedict XVI and called for "fraternity" among Catholics.
"It seems that my brother cardinals have gone to the ends of the earth (to find a pope)," Francis said, referring to his native Argentina, which erupted in celebrations at his appointment.
"Now, we take up this journey... A journey of fraternity, of love, of trust among us," he said.
The former Jesuit priest had barely figured in the pre-vote speculation, although he is believed to have finished runner-up to Benedict in 2005.
World leaders hailed the election of a pope seen as a moderate conservative who chose to name himself after the ascetic St Francis of Assisi.
US President Barack Obama said Bergoglio was "a champion of the poor and the most vulnerable among us", while Philippine President Benigno Aquino said Francis offered "boundless promise".
Argentina's President Cristina Kirchner wished her fellow countryman "a fruitful pastoral mission."
The election was seen as recognition of the Church's rapid growth in Latin America, which is now home to 40 percent of the world's Catholics, in contrast to its decline in Europe.
There had been growing calls both within and outside the Church for the next pope to come from the southern hemisphere for the first time, but Bergoglio ranked just 40th on one bookmakers' list of pre-conclave favourites.
The Vatican said Francis's inauguration mass would take place on Tuesday -- a significant date in the Catholic calendar because it is the Feast of St Joseph, patron saint of the universal Church.
The Argentinian of Italian descent became the 266th pope after Benedict stunned the world in February with his decision to resign.
Benedict's reign was riven by scandals and the new pope will face immediate challenges -- chiefly stamping his authority on the Vatican machinery and trying to coax back a Catholic flock that is deserting churches across the West.
The scandal of hushed-up sexual abuse of children by paedophile priests going back decades has also cast its shadow over the conclave.
One US-based victims' group, SNAP, urged the new pope to declare "zero tolerance" for sex crimes.
Benedict, 85, will retire to a former nunnery inside the Vatican.
Francis has already called his predecessor and they will meet soon, the Vatican said.
In one of his last acts as pope, Benedict issued a decree allowing cardinals to bring forward the date of a conclave in the event of a pope's resignation -- a move seen by many as potentially setting a precedent for ageing pontiffs in the future.
Vatican experts said the prospect of future resignations could have encouraged the cardinals to elect an older candidate in the knowledge that he could step down if his health fails.