For at least a few more years, the Dominion Public Building, which sits across from Union Station, will continue to do what it's done since it was completed in 1935: house federal government offices.

But by 2021, the workers will be gone, moved to offices elsewhere in the GTA, and the building — sold for $275.1 million to private real estate company Larco Investments Ltd. in March — will begin its next chapter.

That's raising several questions about the fate of the historic building. What are the company's intentions for the property? What will Larco do to respect the iconic structure's heritage designations? How well do those designations protect the site? And what more is the city doing to make sure it's preserved?

Larco, one of Canada's biggest real estate developers, has shopping malls, high-end hotels, storage facilities, offices and apartment buildings in its portfolio.

So far, the company has given no clues as to what its plans are for the historic building, which is zoned for commercial-residential use. It could have a tower as tall as 137 metres added to it, according to building regulations.

That's why some experts are asking what could become of the Dominion Public Building — a structure described in a city report as "a rare and exceptional example in Canada of Beaux-Arts Classicism."

The Dominion Public Building, seen in this 1955 photo, was built between 1929 and 1935 and is described by the city as a 'rare' example of Beaux-Arts Classicism. (Toronto Public Library)

What protections are in place?

The limestone-clad structure, with its grand arches and doric columns, is already designated as a heritage building twice over, both as an individual site and as part of the Union Station Conservation District.

The city is also taking steps to designate it a third time to preserve aspects of its interior, including the marble lobbies and bronze doors.

That application was submitted in January, but as city spokesperson Bruce Hawkins told CBC Toronto by email, it won't be complete until the city solicitor brings forth a bylaw to council.

"Once approved, the building is designated," he explained.

The City of Toronto is seeking to protect interior features of the Dominion Public Building under the Ontario Heritage Act. (City of Toronto Archives)

For Kaitlin Wainwright, director of programming at Heritage Toronto, those designations are evidence of a good system of "checks and balances" for any application to renovate or build that Larco might submit.

Not only will applications be discussed by community and city council, the public will also have an opportunity to weigh in.

"We're a lot better now than we were say 30, 40, 50 years ago when it comes to consulting with communities," she said.

How powerful are those designations?

The public's engagement with that consultation process is the most powerful aspect of a heritage designation, according to the Ontario Association of Architects president John Stephenson.

Designations guarantee any applications made by Larco will be subject to "delay, consultation and input," he said, and lay out what specific aspects of the building are considered valuable by the city.

But ultimately, said Stephenson, "there is no absolute protection … there is no absolute prohibition."

In the end, it's a sharp-eyed public that can have an impact on whether undesirable redevelopments are able to take off.

"The power of the designation is that it opens the door to this public conversation which is so critically important," he said.

"Developers, at the end of the day, they are concerned about being perceived well in communities where they develop."

What do we know about Larco Investments Ltd.?

The Vancouver-based company has purchased both government buildings and heritage property in the past — a good sign, according to architect Catherine Nasmith, president of the Toronto branch of Ontario's Architectural Conservancy.

"You don't buy all that real estate of wonderful buildings ... with the intention of tearing them down," she said.

In 2013, one of Larco's affiliate companies bought the iconic Fairmont Chateau Laurier hotel in Ottawa.

Last year, they inadvertently opened up a fierce debate in the city by proposing a modern glass addition to the hotel.

With the issue still not settled, the City of Ottawa launched a public consultation this past winter to continue gathering public input — a good example of how public reaction can help shape redevelopment, said Stephenson.

View from Confederation Square of the Chateau Laurier in Ottawa. Larco caused a stir when it proposed a modern addition to the iconic hotel. (Larco Investments Ltd.)

Larco Investments Ltd. also landed in the news in 2014, when CBC obtained documents that revealed that a big-ticket deal in which seven office buildings were sold by the federal government to the company led to bickering and legal threats.

What is the building's potential?

With numerous examples of well-executed heritage property redevelopment in Toronto, it's not time to man any battle stations just yet, experts say.

In fact, Wainwright of Heritage Toronto said there's reason to be excited about what redevelopment could bring to the Dominion Public Building.

"We've seen a lot of really interesting transformations of historic buildings. I think of 5 St. Joseph, up on Yonge street, and the entire distillery district," she said.

Whatever its new function turns out to be, it could lead to more people enjoying and engaging with the historic building, said Wainwright.

The Distillery District during its annual Christmas market, cited by Kaitlin Wainwright of Heritage Toronto as a good example of how redevelopment can lead to greater public engagement. (Toronto Christmas Market)

Nasmith is also interested to see what approach Larco takes, pointing to "sensitive" development around Summerhill station, where a former railway station was turned into an LCBO location, as a good example for them to follow.

If adding a tower is the route they take, Stephenson has his own piece of counsel, advising them to look to areas like the entertainment district for examples.

"Important mid-rise buildings are being preserved, and yet the air-rights above are being utilized for densification. So there are lots of examples for how it can be done," he said.