En Masse. On Saturday.

The mass roll-a-thon will take place between 10am and 10.30am on Saturday, with possibly hundreds of people rolling down the grass at the one time.

The Rolling Down the Hill event is the brainchild of architect Lester Yao who only dreamed up the idea on Monday and by Thursday had close to 2000 people on Facebook expressing an interest in attending.

Mr Yao, 34, doesn't want the event to get too political, preferring it to be a "day of fun and freedom".

But he still has some firm views on plans for an anti-terrorist fence - which may or may not prevent people from walking on the grass in the future, the details still under wraps.

"People say there may be a gate in the fence but that still undermines the intention that we are now free to go up ourselves," he said.

"Even with a gate, there's still someone in judgement - 'Are you the right kind of person to walk on these lawns?'."

As an architect, Mr Yao also appreciates the intention of the late Aldo Giurgola to design a parliament house where the people could literally walk over the representatives they had elected.

"It's a very simple gesture but a very powerful one," he said.

Originally from the Philippines, Mr Yao said he recently took a visiting cousin for a tumble down the hill, which got the ball rolling on a mass event.

He said travelling overseas and returning home, he never got over the fact of "how good we have it here". Rolling down a hill was a simple way to celebrate our freedom.

Mr Yao advised people to keep an eye on the Rolling Down the Hill Facebook page to confirm the event would continue if the weather turned for the worse.

At the moment, anyone can still walk up and down the lawns - and roll down them - with the exact details of the fence still to be released.