Thousands of public servants will begin moving into Brisbane's "Tower of Power" today with the interior of the building complete.

1 William Street in the Brisbane CBD is ready for more than 5,000 government bureaucrats and staff, including the Premier and her Cabinet, to relocate to.

Staff will move into the building over the next six weekends.

The $650 million, 41-storey skyscraper named the "Tower of Power" was commissioned by the former Liberal National Party government in 2012.

High winds and rain delayed the completion of the privately owned building, which was originally expected to be finished in September.

Paul Krautz helped lead the 1 William Street project in Brisbane. ( ABC Brisbane: Terri Begley )

Program director Paul Krautz said the controversial shape of the top of the building, dubbed the "lipstick", allowed multiple verandahs to be created.

"When the architects were designing it they wanted the top three levels to be verandahs, so each top level can look out over the river," he said.

"The top level will be for functions and then the Premier and the Deputy Premier's floors will sit under that.

"We've been told there are very good views out and over to the ocean."

Highest commercial building in the city

Developed by Cbus and built by Brookfield Multiplex, the building is 260 metres tall including the spire, making it the highest commercial building in the city.

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"All the floors will be occupied by State Government agencies including trade and investment Queensland," Mr Krautz said.

"The public area around the foyer is open to the public and there's meeting levels in the building also."

Old government buildings including the Executive Building, Public Works Building and Neville Bonner Building will be demolished to make way for the Queens Wharf integrated casino development.

Mr Krautz said furniture and items from those buildings could be reused.

"The new building has a whole new fit out," he said.

"Yet the old furniture from the buildings that can be reused will go to Department of Housing and Public Works into other refurbishments that they're doing."

Queensland biomimicry throughout the levels

Each floor of the building has been themed in the flora and fauna of Queensland.

"The designers called it biomimicry, so one floor is the green tree frog floor and another is the barramundi," Mr Krautz said.

"It's good as it helps you find your way around the building."

Construction workers are still working on the exterior of the building.

"The outside of the building should be finished in the next four to six weeks, but the inside is completely fitted out ready for us to move in," Mr Krautz said.

When it comes to the official name, he said the building will be known as 1 William Street.

"That is the final name ... 1 William Street — not lipstick or any of the other names we've been hearing — this is it."