It has seen nine premiers come and go, hosted cabinet meetings for 45 years, and been the epicentre of government in Queensland since the rule of Joh Bjelke-Petersen

But today is the last time the former Executive Building at 100 George Street will open its doors to the public.

Those people who managed to get tickets to the sold-out tours will see parts of the building not normally accessible to the public, including the premier's offices and the cabinet room.

The Executive Building was first proposed by the Queensland government in the 1960s.

The plans included shaded windows, shadowed walkways and exposed columns to "express the subtropical Brisbane climate and contrast with the unsuitable glass boxes of the past decade", as one senior architect put it.

It was built with a three-level basement which could be easily adapted into radiation fall-out shelters

The building was officially opened on April 27, 1971 by premier Sir Joh Bjelke-Petersen, with a cabinet meeting held inside that afternoon.

The first cabinet meeting was held at 100 George Street on April 27, 1971. ( Supplied: Courier Mail )

Sir Joh's citadel

Being the centre of power in Queensland, the Executive Building attracted its fair share of controversy.

In 1985, it was referred to as "Sir Joh's citadel" in the Sydney Morning Herald, after lights in the former premier's office stayed on despite widespread power outages.

The controversy came during the South East Queensland Electricity Board industrial dispute, one of the biggest in Queensland's history.

"While Brisbane people have been reduced to barbecuing sausages taken dripping from electricity-starved refrigerators, the Executive Building from which Sir Joh Bjelke-Petersen rules his state has arrogantly shone out in a sea of urban darkness," the newspaper wrote in February 1985.

The lights stayed on in the executive building while Sir Joh did "battle with his favourite kicking boy, the unions", because the building runs on its own generators.

Letter-bomb attack

The Courier-Mail reports on the letter-bomb incident in 1975. ( Supplied: Courier Mail )

100 George Street itself came under attack in 1975 when a letter-bomb addressed to Mr Bjelke-Petersen exploded on the 14th floor.

It injured two mailroom officers.

At the time The Courier-Mail newspaper reported that it marked the end of "the free and easy days" for the premier.

A second bodyguard and a bulletproof vest were allocated to Joh after the incident.

The Executive Building also housed the Fitzgerald Inquiry into alleged police misconduct.

The landmark probe went for two years and resulted in jail terms for four ministers, convictions for high-ranking police and Sir Joh being charged with perjury.

Demolition teams waiting

The Executive Building will be demolished to make way for the Queen's Wharf development. ( Sourced: destinationbrisbaneconsortium.com.au/ )

After today's open day, the Executive Building's doors will close for the final time.

The building is slated to be demolished next year, to make way for the $3 billion Queen's Wharf development.

With it goes more than four decades of history from deep within the Queensland Government.