Deep underground in Melbourne's Arts Centre is a bathroom off limits to the public.
Tiled in royal blue from floor to ceiling, and featuring two huge mirrors laced with lights, this bathroom was built for royalty.
And it was anticipated the first person to use it would be Princess Diana.
But she refused.
The bathroom was built as part of the new Melbourne Concert Hall, a landmark venue that opened in 1982 and is now known as Hamer Hall.
Shortly after the building's official opening, a concert was held in 1983 for Princess Diana and Prince Charles who were touring Australia at the time.
The Royal Gala was hosted by Bert Newton and featured performances from Marcia Hines, John Farnham and Peter Allen.
Claudia Funder, who now works at Arts Centre Melbourne as a research coordinator, performed at that concert and recalls the "air of excitement".
"I was in the Melbourne youth choir and we were singing with Marcia Hines," she said.
"It was a venue Melbourne never had before in the tradition of Broadway and the West End."
A bathroom made for Diana to enjoy
When they weren't watching the performance, Princess Diana and Prince Charles spent time in the private function room, the Truscott Lounge.
Designed by festival director and theatre designer John Truscott, the room's walls are draped with luxurious green velvet, finished with a gold ceiling.
"The space is the exact shape of Hamer Hall if you were looking down on it — a weird egg shape," Arts Centre Melbourne tour guide Emma Whitby said.
"If you're coming to a private function before or after the show, you can have drinks and see everyone going into the stalls or queuing for the bar."
And through a door off the side of this room is a bathroom.
"The toilet was made specifically for Princess Diana to enjoy," Ms Whitby said.
"It was filled with flowers and toiletries exclusively for her."
Ms Whitby said the story goes that Princess Diana was enjoying drinks with everyone in the function room — but became embarrassed to use the toilet.
"They told her the flowers and toiletries had been picked especially for her," Ms Whitby said.
Princess Diana then spoke to security and told them she wanted to use another bathroom.
"They took her back to the public foyers to use the public toilet, and cleared out the audience in there," she said.
"I find it weird that we know this, but it was noted how many times she went to the toilet — it's recorded that she went to the bathroom twice, and each time they had to clear it out due to safety reasons."
Ms Whitby said the toilet Princess Diana used in 1983 did not exist anymore.
"We used to have 35 toilets on that floor, upped it to 67 but then tore out the existing toilets," she said.
Toilet represents Melbourne becoming a cultural capital
For Ms Funder, the story of Princess Diana and the bathroom "symbolises so much more" than just bathroom business.
It was about Melbourne having a theatre — and a bathroom — fit for royalty, something the city didn't have previously.
"Where were the concerts previously? The Melbourne Town Hall. And have you seen those toilets?"
Ms Whitby said the story had been recorded in Arts Centre history and was a favourite for those who took a tour of the theatre.
While the space is not freely accessible, it is a stop on the Arts Centre tour for both school groups and the public.
"All the tour guides know this and talk about it," she said.
"Public tours aren't back yet after COVID, but hopefully they'll be back soon."