All 581 apartments sold within five hours at the launch of a new development in Darling Harbour on Saturday.

Buyers queued from 8am and forked out more than $600 million to secure a slice of the Darling Square project.

Even the two penthouses found buyers who paid more than $10 million each to nab the top spots in the development.

"It's amazing," said managing director of urban regeneration for Lend Lease, Jonathan Emery. "We've had a huge turnout. There was a great level of excitement."

Mr Emery said Lend Lease had brought forward this second release of 581 apartments in their Darling Square project following the first release of 538 apartments last year which also sold out in a day.

Lend Lease's Darling Square project is a mixed-use development of three buildings, including retail, commercial and public spaces. It is part of the $3.4 billion revitalisation of Darling Harbour.

The Alex Tzannes-designed apartments with Bates Smart interiors will have expansive north-facing harbour and city views.

Residents will share an open-air heated infinity pool, deck, gym, grassed areas and barbecue facilities.

When complete, Darling Square will have about 1500 apartments, 4200 residents and 2500 workers.

Prices ranged from $800,000 for a 50 square metre one-bedroom apartment, to $10 million-plus for the 400 square metre four-bedroom penthouses.

"We have introduced the sky-home apartments this time which are larger," said Mr Emery. "The mix is more three- and four-bedroom apartments. They've sold very strongly."

Mr Emery said the emergence of urban living is crossing boundaries. "It's not just singles and young people. There's a great diversity of buyers coming to the inner city for its convenience and amenity."

The chairman of residential at CBRE, Justin Brown, said there was a generational shift towards living in the centre of the city, with Darling Square, Barangaroo, the redevelopment of Circular Quay and the proposed George Street tram all key drawcards.

But competition to live in the CBD will be stiff, he said.

"The CBD is the most undersupplied marketplace in Australia."

The apartments sold on Saturday are due for completion in 2018.

"We have one more release planned," said Mr Emery. "We'll reflect on customer feedback today to evolve our next release."

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