Demolition work was expected to start on Wednesday to remove the glasshouse, which has been a key feature of the gardens for more than 40 years and will now be replaced by the multi million dollar display space.

The doors of the pyramid were shut two and a half years ago after it was deemed unsafe under building regulations. It was opened in 1972 and had outdated heating, cooling and ventilation technology, no disability access and little room for larger plants to grow.

Relocating the 17-metre high pyramid within the gardens was ruled out. The dismantling is expected to be a slow and delicate process that could take a month.

It will clear the path for the development of the exhibition centre, which has been dubbed "a living art gallery and a theatrical experience".

The centre will be built around the current Arc glasshouse, extending onto the site of the pyramid, and is expected to be officially opened in June 2016 in time for the garden's bicentenary.

It will be a mix of indoor and and outdoor areas and host changing themed exhibitions such as "Who wouldn't be intrigued by Plants that Kill?" and "What child could stay away from The Enchanted Garden?".

It is unlikely to technically function as a 'biome', as it was so-called when funding was announced for the development by the state government in 2013.

The centre does not have an official name yet but is using the working title of the 'Horticulture Exhibition Centre'.

The cost of the total project is unclear, although the state government pledged $17 million funding and philanthropic and corporate sectors are also contributing.

Director of horticultural operations Jimmy Turner said the centre will forge fresh links between the gardens and the city, residents and tourists.

"Both the centre and the exhibitions will attract people who haven't had a good reason to visit before, engage them in a way they wouldn't expect, and challenge and change their views on plants, the environment, people and life," he said.