
I had no idea what it was until recently. I believe it was the base for a large steel radio mast for the Townsville Radio Station which was located in the reinforced concrete building which is now Souths Football Club House in Victoria Park. The Townsville Radio Station was established by the Coastal Radio Service in 1913.
During WWII it came under the control of the Royal Australian Navy.
The US Army also established what they called Camp Victoria Park near this Radio Station during WWII.