In 1919, just over 4000 patients were treated in the building when its Great Hall was turned into a makeshift hospital.

Harold Jewell, who was 10 at the time, was quarantined there alongside his father and brother.

"People died like flies," he later wrote, describing orderlies coming in day and night with stretchers, removing dead bodies, and marching through the aisles to a holding room; the basement became a temporary morgue.

"The empty bed was very quickly filled. We were amongst the fortunate survivors."

Beds for female patients were between the concert platform in the west and the dome; male patients were in the spaces beyond. It was a grand yet draughty, spartan space; each bed had an electric light slung over it from wires festooned above. Nurses reportedly appealed to the public for pot plants and flowers "to brighten the cavernous wards".

Cubicles were set up in the banqueting room and committee rooms for the nurses’ quarters. Some also slept on verandas behind the western annexe.

Before being allowed to leave, recovered patients were subject to a "fumigation" with steam and eucalyptus, said Jewell. "We were put into a steam-heated room with other discharged patients to ensure that we were totally free from any contaminating virus."

Between the temporary hospital opening in February 1919 and closing that August, 392 people died. According to Museums Victoria, an estimated 12,500 people died of Spanish flu in Australia. Others put the number as high as 15,000.

Built of brick on a bluestone base, the Royal Exhibition Building cost £250,000 and was built by David Mitchell (Dame Nellie Melba's father; she would perform in the building in 1907).

Reed's design was inspired by an architectural style known as Rundbogenstil, popular in Germany in the early 19th century: a round arched style that calls on elements from the Byzantine, Romanesque, Lombardi and Italian Renaissance. The dome was modelled on Brunelleschi’s 15th-century cathedral in Florence.

From its inception, the building has been used as a venue for exhibitions, from home, pet and motor shows to the annual Melbourne International Flower and Garden Show and Melbourne Fashion Festival.

Along the way there have been many memorable moments. In 1930, for example, during the Great Depression, Sidney Myer provided Christmas dinner on site for 11,000 poor and unemployed people.

From 1940 to 1946, the RAAF and the WAAAF took over the building and surrounds. The RAAF left a series of Nissen huts, which became an accommodation centre for newly arrived British migrants. Thousands of people stayed there on a temporary basis between 1949 to 1962, awaiting permanent digs in their adopted country.

The Exhibition Building was also home to Australia’s first aquarium.

It was nearly lost in 1953, when a fire broke out, destroying the aquarium and much of the eastern annex. All the fish died and many museum exhibits and building archives were destroyed.

The "royal" in the building's title was bestowed during Princess Alexandra's visit in 1980. World Heritage listing occurred in 2004 and major renovation works have been ongoing since the 1980s.

Plans to commemorate the Royal Exhibition Building's 140th birthday have been pushed back due to COVID-19, but next year will bring the much anticipated opening of the Dome Promenade, when Melburnians can again climb to the top of the building.

Last open to the public in the late 1910s, it was one of the main attractions of the 1880 exhibition, says Stevenson.

More than 4000 people visited on Cup Day, taking in views all the way to Port Phillip Bay.

"The exciting thing about reopening the Dome Promenade next year is that for once rather than being the setting for the story, the Royal Exhibition Building gets to be the main character," Stevenson says.