On the way out from the open day, the visitors offer Lochert and his staff money. For having appreciated the majesty of the building, they have also seen the other side: a building in urgent need of repair.

They are prepared to reach into their own pockets to help.

Behind the gilt and glory is a building that remains stuck in the 19th century in which it was built.

Lifts are unable to take wheelchairs, or ambulance stretchers in an emergency – and that's provided they are working. Wiring from the 1890s is still in use. Offices for MPs are jammed above the library dome, known by the name of "Byelection Corner" – in the event of a fire, MPs would have little chance of escape and byelections would result.

And there are additions like the "chook house" in the gardens – asbestos-riddled offices for MPs built as "temporary" accommodation in the mid-70s. New MPs are warned not to hammer nails into the walls because of the asbestos risk.

So poor are conditions that Parliament House is unlikely to meet many of the occupational health and safety laws that the Parliament itself has demanded of the rest of the community, the result of decades of neglect.

"I often think of this building as being a little bit like an old aunt," says Bruce Atkinson, president of the Legislative Council. "It's a lovely building but does need some care and attention, a little love."

Just how much love was evident on a tour of building by , which took us to the hidden corners above ground and below – including an 1890s tunnel that runs underneath the building.

First the good news. During the past decade, a team of stonemasons had been replacing the sandstone on the building's facade, sourcing the material from as far away as a quarry in Gosford in NSW.

And a project to make the building waterproof is continuing – work has just begun on the rusting roof over the Premier's offices.

Both were desperately needed. Stone had begun falling – in one case, crashing to the ground where former Labor minister Tim Holding and a group of visitors had stood only 20 minutes before.

The building was also leaking. In some areas, paintings on loan from the National Gallery of Victoria have had to be moved. During a storm in the previous Parliament, water hit the portraits of Queen Victoria and Prince Albert above Queen's Hall.

New security gates and entrances on the side of the building have also been installed. An upside is that the entrance is now wheelchair accessible.

The building also now has a disabled toilet – but that was only opened in December last year.

This was a parliament built for the 19th century, when MPs would attend for votes and depart. The chambers were completed in 1856, and the rest was built in stages until 1929, and maintained by the old Public Works Department. When the department disappeared in the early 70s, the maintenance largely ended – few things were done was done until 2005.

The huge backlog of work is evident on our tour, which reveals parts of the building to be a working museum. Electricians have been replacing wiring, and regularly find sections of lead-encased wiring from the 1890s and 1900s still in use.

Byelection Corner is accessed by the lift and stairs. But when the lift is out of order – four times in the past fortnight – MPs must use a spiral staircase. For safety, female MPs often leave shoes at the bottom. When division bells ring, they have only three minutes to make the chamber.

Below ground is a remarkable relic. We are led through the archives room, and squeeze between compactors holding annual reports. A door is opened, and we are met with surge of cool air from below, delivered by a tunnel that runs into the parliamentary gardens.

The 1890s construction was built as a form of evaporative cooling, the air passing through pebbles and water. It wasn't a success, and was soon taken out of operation.

Even with the work that has been done, serious problems remain. "Despite this significant effort to address decades of neglect, the building continues to present significant occupational health and safety risks to members, visitors and staff," Lochert, who heads the Department of Parliamentary Services, said in his 2014 annual report to Parliament.

Legislative Council president Bruce Atkinson shares this concern.  With the Speaker of the Legislative Assembly, talks have continued with the previous and current governments.

A priority is the "chook house", and Atkinson says estimates have put at a replacement at about $40 million. One possibility is using a "sinking fund" Parliament has accumulated over the years.

The thinking is to cut down into the ground, so as to preserve the sight lines to St Patrick's and St Peter's.

One of the problems is the unpopularity of politicians spending money on themselves. "It's not about creating a palace for MPs; it is about ensuring that we have a functional workspace and a safe workspace that is consistent with what you would have in any other workplace, private sector or public sector," Atkinson says.