Federal MPs returning to Canberra next week will get their first look at the near-complete fence across the front of Parliament House, already described as a "monstrosity" by angry politicians.
While construction of prefabricated 2.6 metre and 1.2 metre steel fences around the entire building won't be completed until June 2018, access to parts of the front lawns is now limited.
The fence is part of more than $126 million in security upgrades and fortification works planned for Parliament House.
About 20 mature trees were removed and large trenches were dug in the lawn as part of construction, which has been under way since May.
Approval was rushed through Parliament as MPs prepared to leave Canberra for the Christmas break last year.
Last month a number of MPs who voted for the fence told Fairfax Media they were alarmed by the scale of the structure, but none would criticise the project publicly due to security concerns for the building.
The suite of security upgrades was prompted by a 2014 review, a response to terror attacks against the Canadian Parliament in Ottawa.
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The building's celebrated architect, Romaldo Giurgola, envisaged the lawns of Parliament House as a symbolic opportunity for Australian citizens to walk above their representatives.
Greens MPs and Victorian independent senator Derryn Hinch are among critics of the proposal.
Last month, Tasmanian Labor MP Brian Mitchell became the first major party MP to criticise the fence, despite joining his party and the government in voting to approve it.
"Not the Parliament's finest hour," he said, adding he would "have to wear that I voted for it. Stand by the comment."
"Presiding officers took the view under advice it was necessary - many not happy but we let it through so must wear it."
Speaker Tony Smith and Senate President Stephen Parry have kept secret the total cost and designs of the work since security agencies and politicians agreed on the plans in 2016.
Visitors to Parliament House can still access the rooftop lawns after undergoing security checks inside the main entrance and travelling via lifts to the viewing area.
The fences have been designed to match existing metal work around the Parliament House precinct and includes limited horizontal elements to stop intruders being able to scale the security barriers.
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