Timber walls surrounding the Great Hall celebrate the country's unique physical environment, made of brushbox and jarrah. Outside the front, the forecourt reflects the country's ancient past with a mosaic.

The building's most potent symbol is not its sloping lawns reaching to the top, but the people walking on them.

Architect for Parliament House, the late Romaldo Giurgola, reportedly said if it was to speak honestly of its purpose - democracy - it could not be built on top of the hill, as this would symbolise government imposed upon the people.

"The building should nest with the hill, symbolically rise out of the Australian landscape, as true democracy rises from the state of things," he said.

How could a 2.6 metre-high fence be raised across those lawns and not be interpreted as a symbol? The entire building was carefully given meanings. The fence inevitably invites public definition too.

Much has already been made of the undemocratic overtones of the security fence, not helped by the lack of public consultation about its installation and the secrecy surrounding the reasons the government moved so fast to build it, pushing the necessary legislation through before Christmas 2016, when few were looking.

It's hard to argue with a security assessment that few outside government has seen. Architects backed down on opposing the fence after they received a confidential briefing, only making the information they saw more intriguing.

Granted for now that the public contents itself that the government has a good reason to build the fence, how does Canberra welcome this new addition to its landmark building? What does it say not just about Australia, but the national capital?

The fence does say something about Australia's role in the world, having joined in enough wars trying to stamp out terrorism to make it a target for the likes of the so-called Islamic State and other organisations. It also means the government considers Canberra, a quiet city planned carefully to respect its natural surroundings and provide an ordered, calm seat of government, as a potential theatre in the clash between terrorism and Western nations. That is a milestone for Canberra.

But any claim that it's a loss of innocence would be overblown. Whether the fence is undemocratic in meaning is debatable - these ideas could be rejected with an argument that democracy continues, but needs greater protection now. The fence isn't necessarily forever either. There may be a time when the city can dismantle it and walk to the top of the sloping lawns again. Until then, Parliament House will take on new meanings and Australia's growth will make Canberra itself more visible to the world.