To passersby on the footpath on Barrack Street, in Perth's central shopping district, all that's visible is a modern looking men's hairdresser.

But when you duck around the laneway, there is a hugely popular toasted sandwich cafe squeezed into the tiny backroom and courtyard.

If you look upstairs, the building is a rare 120-year-old surviving federation Romanesque building that was once a pawnbrokers shop and family home.

After six years of careful conservation work by the owner, Peter Rossdeutscher, the building is now taking on a new life as an office space for creative professionals and has just been placed on the state heritage register.

"It was constructed to be a pawnbroker, it was specifically built as that and is the only purpose built one that we know of left in WA," explained Penny O'Connor, the WA State Heritage Office's manager of assessments and registration.

It was commissioned by Phineas Seeligson and built in 1894 to designs by Henry Trigg, the first architect to be born and trained in Western Australia.

"Phineas Seeligson was a very prominent person in the Jewish community of Western Australia and he was a pawnbroker and he decided to have this building built," Ms O'Connor said.

"Pawnbroking was a really important part of the financial system of the day, banks in those times weren't as flexible with lending of money.

"Today there are all sorts of different ways that you can borrow money now; through a credit card or a personal loan.

"But in the late nineteenth century the opportunities for people to borrow money were far fewer, so pawnbrokers actually provided a really important service in giving small flexible loans."

Phineas Seeligson's building on Barrack Street, c1894. ( Supplied: State Library of WA )

Historical photographs show that, from the beginning, the building had a sign reading City Loan Office on the side.

Mr Seeligson also featured regularly in newspaperis it the name of something?

reports of the time, giving evidence in court on matters of stolen property; in 1908, he sold the pawn broking business to Albert T Jones, who ran the business with his brother-in-law Ernest Dyson.

Mr Dyson also lived in the upper floors with his family until the business moved in 1930.

Between 1930 and 1969 the shop at 143 Barrack Street was occupied by a wide variety of businesses; including Cafe Nanking (one of Perth's first Chinese restaurants), a butchers shop, a self-proclaimed naturopath, a record store and an early branch of the ANZ bank in the 1950s.

Dormant for 50 years

By 2008 the current owner, Peter Rossdeutscher, bought the building and set about conserving and activating every floor of the building, which apart from the hairdresser on the ground floor had been untouched for decades.

"My concern was that it was in a bit of a state and a friend of mine who is a conservationist thought there was a chance we could lose the building so I thought, alright, I'll invest in that," he said.

143 Barrack Street - the back of the building is now a cafe. ( 720 ABC Perth: Emma Wynne )

"I bought it just because I thought it was super cool. I used to see it when I was a kid and I didn't want to see it disappear.

"I was fortunate, the building hadn't really been impacted. It has sat there dormant for 50 years, and all the original bits were there."

What followed has been a seven year labour of love, involving a detailed conservation plan, a painstaking restoration of the Romanesque facade of the upper level of the building and bringing in new tenants to get the building used.

"The biggest thing was how to activate the building. The main thing in heritage is if a building is being used, it gets looked after. When buildings are sitting there idle is when you have a problem," Mr Rossdeutscher said.

The building received a surprising boost when the owners of cafe called Toastfaced Grillah decided the back room and tiny courtyard would be perfect for their business.

"These guys came along and I never thought it would work to be honest. They managed to drag people into the lane and it's one of the busiest cafes around now," Mr Rossdeutscher said.

"It activates the back lane as well, which is part of the City of Perth's strategy."

Mr Rossdeutscher said the building, now called "Toastspace", is used from on all four levels.

"On the upper floors of the building there are a lot of small businesses, it's a cohabitive workspace, for creative people working in music, arts, things like that," Mr Rossdeutscher said.

"We are calling the building Toastspace because the cafe is very famous now.

"It's very full. The basement is used for meetings, bands go down there and shoot their videos; then out the front is still the men's hair dresser, they have been there for at least 15 years."

On the first and second floors, there is a window into the past with the rooms turned into offices but with their nineteenth century features still on display.

The two rooms at the top, which fit under the steeply sloping roof, retain their charm and views of the city rarely seen by the public.

"These two rooms are what convinced me to buy the buildings, and that view — that blend of old and new buildings," Mr Rossdeutscher said.

The top floor in the attic is now a shared office space. It would have originally been the children's bedroom when the building was a home. ( 720 ABC Perth: Emma Wynne )

Restoration and re-creation

Restoration has been a challenge; floorboards are not produced in the same width anymore and all the fittings, like the built-in desks, have to be potentially reversible in a heritage building.

Mr Rossdeutscher has further plans; like potentially recreating the balcony and persuading the Perth City Council to put in a bollard that blocks the laneway to vehicles during the day, allowing the cafe to spill out onto the laneway.

Penn O'Connor, manager at the State Heritage Office, believes the restoration of the building has been a triumph.

"It's really important that we firstly identify these places and then work with the owners to try and conserve them into the future," she said.

"In the case of this building it has a very committed owner, and he certainly values the building himself and has done some fantastic conservation works to it.

"Which means that it looks, today, in really good shape and [is] in a good place to continue into the future."