On July 22nd 2011, the right-wing extremist first set off a bomb near the government building in Oslo, killing eight people, before going on a shooting rampage on the nearby Utøya island, where the ruling Labour Party's youth wing was hosting a summer camp.
He killed 69 people on the island, most of them teens.
To mark the first anniversary of the massacre, religious ceremonies will be held across the usually peaceful Scandinavian country, wreaths will be laid at the sites of both attacks, and there will be a concert near the Oslo city hall.
Prime Minister Jens Stoltenberg is set to attend a service at the Oslo cathedral, alongside the royal family, and to give a speech to Labour Party youth on Utøya.
Shortly after the worst attacks in Norway since World War II, the Labour Party leader made a deep impression with his vow — reiterated many times since then — that Norway's response to the bloodbath would be "more democracy, more openness and more humanity, but never naivity".
"What Stoltenberg achieved with his well-chosen words was to set the tone for our national reaction after the catastrophe. He contributed to avoiding that the atmosphere became filled with hate and coloured by thirst for revenge," a commentator with Norway's paper of reference, Aftenposten, wrote on Wednesday.
"We can ask ourselves whether the most important thing after July 22nd was not the preservation of what we have. For we have for many years been able to enjoy living in an all in all well-functioning democracy, with more openness and freedom of speech than most other countries in the world," he said.
Besides a few minor measures like legal amendment proposals and hiked protection for high-level politicians and seats of power, Norway has not noticeably increased security or limited public access since the attacks.
One can for instance still sometimes spot cars parked right outside the entrance to parliament.
"Norway has not changed," said Trond Henry Blattmann, who heads a support group for the victims' families and who himself lost a son on Utøya.
"We can in any case never build fences high enough to protect us completely," he told AFP, but added that he nonetheless hoped a commission created by the government last year to draw lessons from the massacre would inspire some changes, "like improved online surveillance and better surveillance of the extreme right to prevent future attacks".
The July 22 commission is scheduled to present its conclusion on August 13th.
Among the survivors of the island massacre, opinions differ.
"What has changed in Norway? Not enough," said Tore Sinding Bekkedal, expressing disgust at the virulence of some of the reactions to a group of Roma camped out in the heart of the Norwegian capital who have been the subject of heated debate in recent weeks.
"These opinions should be met with a much harsher response," he told AFP.
Bjørn Ihler, another survivor of the shooting massacre, meanwhile insisted that extremists must be permitted to express their ideas freely to avoid the creation of underground enclaves.
"After the attacks, we promised more openness. Everyone must therefore be allowed to express their opinions, regardless of how extreme they are. People who are critical of immigration must be permitted to say so without being associated with July 22nd," he told AFP.
Breivik, whose 10-week trial ended last month, is meanwhile awaiting his verdict.
While there is no doubt he carried out the attacks, the five Oslo court judges must rule on whether the 33-year-old should be considered criminally sane and sentenced to prison, as requested by his defence, or instead follow the prosecution's line and send him to a closed psychiatric ward.
His verdict should be announced on August 24th.