Purpose-built in 1928, when Mount Stromlo was considered a remote location, the house was almost ruined when the ferocious January 2003 firestorm swept through Canberra from the west. It has now re-opened to the public after a $1 million restoration project.

ANU's Research School of Astronomy and Astrophysics director Professor Matthew Colless is happy that the building has re-opened but he won't miss living there, even though the founding director, Walter Duffield, and his wife, Doris, relished their residence in the mountains. Seven other observatory directors have also lived there.

"No, I don't like living above the shop," Professor Colless said. He was appointed in 2013 as Mount Stromlo's 10th director. "I'm a fan of getting away from work when I'm not actually working. I myself would not have liked to live here, so the fact it is not a working residence doesn't bother me in the least."

Professor Colless was on the staff at Mt Stromlo and was playing cricket when the firestorm destroyed the residence and five telescopes. He tried to get to Mt Stromlo, was turned back by huge flames and returned to protect his home in Rivett.

Gone is the residence's interior grandeur, including a beautiful jarrah staircase and flooring. Instead, walking inside triggers audio visual presentations including "Eyes on the Sky" featuring an interview with Nobel prize winner Professor Brian Schmidt.

ANU heritage officer Amy Jarvis said the residence's restoration took a little longer because it was not as pressing as getting the research school back on its feet after the fires, or investment in new scientific instruments.

After winning almost $500,000 in Commonwealth grants which the ANU matched, Ms Jarvis and Professor Colless are excited that the public can come inside to see what happens at Mount Stromlo.

"The more people we get up here, the more people get to know what we are about, and to realise we are here and see this is a living, vibrant site, not some musty old museum," Professor Colless said.

Ms Jarvis said water had entered walls, and trees and vines had found their way inside the burnt-out building, which has since been reinforced with steel and straps to secure the original Canberra red-brick walls.

"We were left with an opportunity to stop it from falling down and leave some flexibility to what it could be in the future," Ms Jarvis said. "In the meantime, people can access it for the first time ever. Because it was a private residence, there's never been public access to this building."

Restoration has included a red Marseille tile roof with a pattern like the 1928 original roof.

The building is covered by the precinct's Commonwealth heritage listing and each of its rooms has a label explaining what its original function was, while original plans of the house are on the wall.