The mall's owners say the new Legoland Discovery Centre, due to open in mid-2017, will cover a massive 2800 square metres, equal to about 30 averaged-size homes, and will boast interactive rides, play areas and even a small cinema to keep the kids occupied.

It's designed to entertain three-to-10 year olds for up to three hours.

The Chadstone Lego centre will make be the first discovery centre in southern hemisphere for Lego, which was described in January by Forbes' Fast Company publication as "the Apple of toys".

The Australian store will join a global network of Lego Discovery Centres operated by British group Merlin Entertainment, including nine in North America, four in Europe and two in Japan.

The Chadstone mall itself is undergoing a $600 million redevelopment that will add an adjoining office tower and apartments. Once completed, it will be the biggest mall in the country.

The Lego centre will be adjacent to the main cinemas in the new $25 million-plus wing under construction.

"It could become Australia's version of the New York's FAO Schwarz," said Zelman Ainsworth, head of Melbourne retail leasing at property group CBRE.

Made famous in the Tom Hanks movie Big, the iconic New York toy store closed its doors in July, blaming high Manhattan rents.

"Legoland is a creative retail store which is about the experience and not just the product," Mr Ainsworth said.

"It's a destination retailer that brings a fresh new element to a shopping centre."

Merlin's chief new openings officer John Jakobsen said the discovery centre concept has been a huge success worldwide, offering a family day out of shopping and dining.

"We have no doubt that the centre will be popular in Melbourne, and we are delighted to be working with Federation Centres on this exciting new project," he said.

"Australia and Asia are very important development areas for Merlin.  We already have a cluster of exciting attractions in Sydney and now we want to build our business here in Melbourne, which is a vibrant, exciting city with a high proportion of families with young children, all looking for high-quality leisure options."

The group's Sydney attractions include Madame Tussauds and Sydney Aquarium.

As well as rides and places to build with Lego, the Chadstone centre will include a cinema, facilities for birthday parties and a "Miniland" feature that showcases the Melbourne cityscape.

Chadstone Shopping Centre general manager Anthony Rafaniello said the new play zone is the first of many for this major redevelopment at Chadstone.