In Germany, the pope's home country, where eight years ago the election of the first German pope in more than 1,000 years was greeted with the headline "We are Pope!", there was surprise but little overt emotion.
"I didn't really think it was possible to resign. But if he feels he's not in a position to continue then it's an honourable thing to do," said Michael Lauber a 58-year-old civil servant entering St Hedwig's Roman Catholic Cathedral in central Berlin.
"It's what anyone else in any other job would have to do. I can't say I'm disappointed," said Lauber.
In Rome, the widespread mourning which greeted John Paul's death in 2005 appeared a distant memory but the news overshadowed the increasingly bitter campaign ahead of national elections due just days before the pope leaves office at the end of the month.
"This is really extraordinary because not since Celestine V has this happened," said Rome resident Emma Nardi, referring to the last pope to leave office voluntarily, in 1294.
"It's an incredible thing, we need to see why he did it. I hope the church doesn't end up like Italian politics," she said.
Germany had an awkward relationship with Pope Benedict, who was born Joseph Ratzinger in the small Bavarian town of Marktl in 1927. Adored by some but by no means all Catholics, he was ignored or actively disliked by many other Germans.
Germany's top-selling tabloid Bild lamented the departure of "our German pope" but the mood, even among Catholic churchgoers, was subdued.
Chancellor Angela Merkel, a Protestant pastor's daughter, was one of the few European leaders who dared to contradict the pontiff in public, criticising him in 2009 for the Vatican's rehabilitation of a bishop who had denied the Holocaust.
But on Monday she said Pope Benedict's decision to step down deserved her "utmost respect", recalling German pride when Benedict was elected pope in 2005 and praising him as "one of the important religious thinkers of our time".
Elsewhere in the Catholic world, Pope Benedict appeared to have earned more respect as a theologian than adoration as a leader -- suffering as always in comparison to his charismatic predecessor, the Polish-born John Paul II.
"We are dismayed because he is a saint and a first-rate intellectual," said Nani Leon, a history professor leaving San Pascual church in central Madrid.
"No one expected this, although he looked very tired."
More progressive successor?
In Saint Peter's Square in the Vatican City, tourists struggled to absorb the news when it filtered out.
"In a religious post the mission should come from God so obviously for us Catholics it has shocked us, it must be because of his health because if not, it is inexplicable," said Sergio Calabrese, a visitor from Sicily.
Benedict attended World Youth Day in Cologne straight after his election, and received a warm welcome when he returned a year later to his largely Catholic homeland of Bavaria.
But a 2011 visit to eastern Germany was dogged by demonstrations, coming after a torrent of headlines about sexual abuse of children by Catholic priests.
Largely due to that scandal, more than 181,000 German Catholics left the church in 2010, followed by more than 126,000 the following year, taking the total number of German Catholics to 24.47 million.
For many of them, Ratzinger was too socially conservative in his previous post enforcing Vatican dogma as Prefect of the Congregation for the Doctrine of the Faith, and as pope.
The German media was never as critical as some of the Anglo-Saxon press, which dubbed him "God's Rottweiler" and "Nazinger" because of his brief, involuntary membership in the Hitler Youth and military service in World War Two, when he was drafted from the seminary.
But Benedict's papacy gave rise to much dissent in the German church and he never enjoyed the wild popularity of the arguably more conservative John Paul II, whose anti-communism was credited with helping to bring down the Berlin Wall.
Christine Mayr-Lumetzberger, who has fought for the right for women to become priests and was excommunicated by Cardinal Ratzinger in 2002, told Reuters she admired the pope's "mettle" for admitting he was too old to go on.
But she hoped for a successor who would treat men and women equally, allowing both to be ordained. "A pope who takes no action on this is lost from the very start," she said.
"Overall I think he was a reasonable pope, he came after a figure who was much loved. I hope he is replaced by someone who is more progressive," said a Catholic man outside St Hedwig's in Berlin, who declined to give his name.
The critical German lay movement "Wir sind Kirche" (We are the Church) said it was essential to choose a successor "who can tackle the polarisation within the Church".
"We need a pope who represents the global Church, as ever more Catholics live outside of Europe," said the movement's spokesman Christian Weisner.
"The biggest problem within the Church today is the Roman Curia, a centre of power, and which for any pope is a huge challenge."
Benedict's resignation was met with incredulity at Munich's Frauenkirche Cathedral, where he was bishop from 1977 to 1982.
"That is a total surprise," said Andrea Wormsdorf, who said she felt "confused and dismayed".
Another churchgoer asked it was a festive prank on German carnival's "Pink Monday".