It looks like Canada's busiest train station is finally in store for renovations.

On Friday morning, politicians from three levels of government unveiled plans to spend hundreds of millions of dollars to fix up and expand Union Station in downtown Toronto.

"I think this is Ontario's most important building," George Smitherman, the deputy premier on Ontario, said at a press conference across the street from the historic station. "And I think it's fantastic that we can be here today, to mark the end of the time when it's all about talk, and the beginning of the time when it's actually about the long-overdue, much-needed revitalization of this worthy asset."

The City of Toronto purchased Union Station in 2000 as part of a plan to revitalize and expand it. Nine years later, the city, together with the provincial and federal governments, now say they will spend up to $640 million for that purpose, depending on projections.

Calling such public transit projects "vital," federal Finance Minister Jim Flaherty said the federal government has put aside $133 million for the project. However, he added that no agreement had been signed with the City of Toronto as of yet.

Smitherman said the Ontario government plans to chip in $172 million for the revitalization plan. More specifically, he said the province plans to spend $92 million to triple the GO Transit concourse space, from 39,000 to 122,000 sq. feet; $33 million to build an underground connection beneath York Street, joining the north-west corner of the station to Wellington Street; and $47 million to buy and restore the upper three levels of the station's west wing.

Toronto Mayor David Miller didn't outline how much the city would spend. "I just want to say thank you on behalf of the people of Toronto," he said, singling out Baird and Smitherman. "It's amazing what can be accomplished when our three governments work together, and today's announcement is symbolic of that."

Friday's pledge adds to the growing list of recent government promises to invest in public transit in the Toronto area, which houses more than five million people.