The Y-block, which was damaged in the explosion and boasts Picasso motifs sandblasted into its brutalist concrete structure, was nominated for the 2016 list published by the conservation organisation Europa Nostra.
It is scheduled to be demolished under a plan announced in January to redevelop the site of Breivik's attack.
“It is always possible to get the authorities to change their minds in such matters, especially by means of public opinion,” John Sell, the organisation's Vice President told Aftenposten as he visited the building on Tuesday. “It is ultimately up residents of Norway to exert pressure on the authorities to preserve this building.”
The organisation, whose President is the opera tenor Placido Domingo, on Tuesday held its annual conference in Oslo.
It will now work to lobby the Norwegian government to preserve the building over the next year.
“Although the ‘seven most endangered' program is no more than two years old, we have already got evidence that we have managed to influence the authorities in several countries to consider alternative solutions,” Secretary General Sneska Quaedvlieg-Mihailović told the newspaper.
“What strikes me after visiting the Y-block, is how the building fits into the surroundings in such a fabulous way,” Sells told the paper. “Meanwhile, the use of materials, with sandblasted concrete, is truly unique. It is an amazing piece of architecture.”
Breivik launched his brutal twin attacks by detonating a home-made bomb parked in a van under the government tower that houses the offices of Norway's then Prime Minister Jens Stoltenberg.
The neighbouring Y-Block was also damaged in the blast.