A sculpture of caretaker prime minister John McEwen will go up in the parliamentary zone to commemorate the long-serving Country Party leader.
But an expert has blasted the decision, calling it unconscionable spending.
McEwen, who was prime minister for 23 days after Harold Holt disappeared while swimming near Portsea in Victoria in 1967, will be depicted in a cast bronze full body statue on a new commemorative pavement at Queen Victoria Terrace's east.
Deputy Prime Minister and National Party leader Michael McCormack told Parliament in March the sculpture would show McEwen standing over two bags of wheat and represent the political leader's long contribution to Australia's trade and to the nation's regional and rural areas.
The 2.1 metre-high statue will be a centrepiece of a commemorative pavement, representing the services and industries of regional Australia and featuring alongside other nationally symbolic monuments on Commonwealth land at the centre of Canberra.
The project coincides with the 100th anniversary of the founding of the National Party.
Contracts to make and install the sculpture and other parts of the commemoration will cost $500,000.
The spending will include $224,000 for head contract services, $130,000 to supply and install the sculpture, $82,000 for the statue's steel base and $33,000 for design services.
Parliament approved the works commemorating McEwen in February and March. The project received the National Capital Authority's approval on August 11.
Site fences will be set up next week and the statue will go up in December.
A spokesperson for Mr McCormack said: "The works will be an appropriate recognition of Sir John's service to the nation, in the same way statues of Curtin, Chifley and Menzies are appropriate recognition of their service."
McEwen, nicknamed "Blackjack", is Australia's third-shortest serving prime minister and was Country Party leader and deputy prime minister for nearly 13 years from 1958.
When Holt went missing, he served as caretaker prime minister until the Liberal party elected John Gorton as its new leader. McEwen remained deputy prime minister until his retirement in 1971.
He is one of three prime ministers from the Nationals, formerly known as the Country Party, and is the party's fourth longest-serving leader.
One of the party's early influential figures, Earle Page, was prime minister for 20 days in 1939 after Joseph Lyons died, and Arthur Fadden's government lasted 40 days in 1941 after Robert Menzies resigned during his first stint as prime minister.
McEwen's sculpture would join those of four other prime ministers in Canberra's centre.
Wartime Labor prime minister John Curtin is depicted walking with his treasurer and successor Ben Chifley near Kings Avenue, and Australia's longest-serving prime minister and Liberal party founder Menzies is portrayed in a sculpture near Commonwealth Park. There's also a statue of Australia's first prime minister Edmund Barton on Kings Avenue.
Front of the line?
Foundation fellow at the Australian National University's Australian Studies Institute and former National Capital Authority cultural adviser, David Headon, said it was extraordinary that McEwen should be chosen over other political leaders for a statue.
Dr Headon questioned the justification for a sculpture of McEwen in the parliamentary zone.
"Like many Canberrans, I would be very interested in the intellectual, political, cultural and social justification for McEwen being placed there," he said.
"This is a man who was a formidable politician, there's no doubt about that, but at the end of the day he was prime minister for a bare three weeks.
"Even though he was a significant leader of the Country Party, and in the Parliament for close to 40 years, neither of these facts justifies the placing of the statue at such extraordinary expense in the parliamentary zone of the nation's capital."
Dr Headon, whose work at the National Capital Authority during the 2000s assisted in the installation of Reconciliation Place and the Menzies Walk, said there was a number of prime ministers who should be commemorated ahead of McEwen.
Among them were Alfred Deakin, Andrew Fisher, Billy Hughes, Joseph Lyons and James Scullin. Dr Headon said Earle Page also had a greater claim to recognition in Canberra than McEwen, among Country and National Party leaders.
"Quite simply, it is impossible to make a credible case for McEwen, and for half a million taxpayers dollars to be spent on it is unconscionable."
Towering figure, or seat warming prime minister?
McEwen, a Victorian MP, is remembered outside his short time as prime minister for his support of high tariffs protecting manufacturing.
As trade minister he's regarded as a political architect of the trade and commerce treaty with Japan that paved the way for an expansion of Australia's trading relationship with the nation. In government he advocated Australia having a closer relationship with Asia.
ANU political historian Frank Bongiorno said McEwen was among the most significant Australian political figures in shaping post-war Australia, in the boom period between the 1940s and the early 1970s.
"Federally, you'd probably place him amongst the top half dozen political figures who are really influential in shaping policy and just in positioning Australia within a changing region in that period," Professor Bongiorno said.
"He was by far the towering figure following Holt's death, but really after the retirement of Menzies."
Professor Bongiorno said that if the criteria for portrayal in a parliamentary zone sculpture was being a significant politician, it would be hard to object to a statue of McEwen.
"Perhaps there is something in the idea that if you're going to have the most substantial or legendary figures within the Labor and Liberal parties, perhaps there should be one there for the Country Party as well."