Is it really true most humans love to destroy things? Olivier Grossetete believes so, but not in the way you might think.

The French artist has been in Sydney since November overseeing the workshops and creation of the astonishing mini -city known as The Ephemeral City at Barangaroo Reserve for Sydney Festival.

The innovative collection of picturesque towers and turrets, made from cardboard and sticky tape, is being built by you, the people of Sydney, using nothing more than cardboard and, sticky tape and a good dose of imagination.

There are just a few finishing touches before all seven structures, from the Central Station clock tower to the French cathedral and possibly a replica of Sydney Opera House shell, are complete. Then things get really interesting. On Australia Day, the demolition of the 18- metre- high towers will take place on- site, removing all trace of what went before it.

Many thousands of Sydney-siders have helped build the city, from young families to teens and couples; and all are invited to see the process through to its inevitable end.

In the 17 years he has collaborated on more than 140 cardboard cities in various international cities, Grossetete says the enthusiastic response to the demolition is always the same.

“It’s part of human nature! The destruction is part of the art, the creation. As soon as we create the work people are already asking, ‘What if it rains? What if there’s wind?’ They’re already thinking of its destruction,” Grossetete says. “We make it all together with the public, so it’s important we all destroy it together.”

Equally gratifying however is the unrestrained joy he always sees on the faces of the participants, who range from young children to grandparents.

“It’s like a big game of Lego, a big construction. We revisit our childhood with great joy. It’s something I can’t do myself but together we can do anything. As a collective we can save the world.”

For those keen just to purely observe the proceedings, the best seat in the house is the flying fox, the world’s first indoor zip line that flies above The Ephemeral City and artist Shaun Gladwell’s impressive large-scale video triptych Skateboarders vs Minimalism.

Environmentalists can take heart: part of the demolition process includes stamping down the 10 tonnes of cardboard ready for loading onto the trucks that will transport it all to a recycling plant.

The Ephemeral City at Barangaroo Reserve runs daily from 1pm–8pm and is free.

The free flying fox runs at the Cutaway at Barangaroo from 1.30pm-8pm until January 22. Closed Mondays.