The observatory was built in 1924 as The Commonwealth Solar Observatory. Mount Stromlo had already been used for observations in the previous decade, with a small observatory being built in 1911 by Pietro Baracchi using the Oddie telescope. The dome built to house the Oddie telescope was the first Commonwealth building built in the new Australian Capital Territory. Until World War II, the observatory specialised in solar and atmospheric observations. During the war the workshops made gun sights, and other optical equipment. After the war, the observatory began stellar and galactic astronomy and was renamed The Commonwealth Observatory.