With security fences set to be built to block access to the lawns of Parliament House next year, hundreds of people converged on the famous grassy slopes to carry out a time-honoured tradition of school children from around the country: rolling down the hill.

Children, adults, dogs and even a pet parrot came together on the hill, rolling en masse together at 10.30am.

The event was organised over Facebook by Canberra architect Lester Yao, who originally intended Saturday's roll to be a small gathering of friends and families.

He said he never expected word about the event to go viral online.

"It was only going to be about 20 friends and families, and now we had more than 600 or 700 people," Mr Yao said.

"Unfortunately, kids might not be able to do this again and they're just enjoying themselves."

While the date that the 2.6 metre security fence - approved by MPs last month - will be constructed is not known, Mr Yao, 34, said it is a shame the grassy lawns will be closed off to the public.

"The idea of the architect was that you could walk up the hill and be on top of our representatives in government, and be able to show that this is democracy," he said.

Among the many hundreds to participate in the mass roll were James French and his two children Alex and Zoe, 13 and 11.

Mr French said the family would often come to the Parliament House lawns to admire the view of the city before rolling down.

"We used to come here a lot when the kids were a lot younger, so we were going to take the chance and reminisce," he said.

"If they're going to be closing off the hill, we might as well take our chance."

Alex said the hill is the best one in Canberra to roll down.

"It's really nicely kept, and it's definitely good to roll down. It's disappointing that they're closing it off," he said.

Gungahlin resident Ian Urquhart brought his parrot Charlie with him to the event, and while he didn't roll down the hill with his feathered companion, he said he liked the idea behind the event.

"It's a bit of whimsy against the idea of what they were doing, because to me, the grassy hill is the whole point behind the design," he said.

"It was a last chance to have a proper look."

While the start of the mass roll was perfectly executed, the roll did see the occasional collision and many people finishing dizzier than when they started.

Nevertheless, they came, they rolled, they conquered.