He is known for his large public sculptures such as Eagle (Bunjil) in Melbourne, Australia and Owl in Belconnen, Australian Capital Territory.
[2] Armstrong is best known for his large public artworks such as the 25 metre high Bunjil (2003) installed on Wurundjeri Way in Melbourne and The Guardians (1987), which stood at either side of the water wall of the National Gallery of Victoria.
An exhibition of Armstrong's prints and sculptures entitled Savage Beauty was curated by Ted Gott and held at Heide Museum of Modern Art in 1999.
[5][8] Armstrong was honoured with a retrospective of his work at the National Gallery of Victoria that ran from August 2016 to January 2017.
[9] Entitled 'An Anthology of Strange Creatures' the show consisted of 40 of Armstrong's works spread across three floors of the NGV Australia.