Fifty years ago, Toronto's skyline was a mere shadow of what stands tall today. There was no CN Tower, no Rogers Centre and far fewer office towers and condominiums.

But 50 years from now, the city's skyline will look even more dramatically different, experts say, as immigration fuels a building boom in four key neighbourhoods: Bloor St. and Kipling Ave. in Etobicoke, Yonge St. and Highway 401 in North York, Yonge St. and Eglinton Ave., and McCowan Rd. and Highway 401 in Scarborough.

Hundreds of thousands of residential units are expected to go up in these neighbourhoods as urban density replaces suburban sprawl.

Robert Freedman, the city's director of urban design, says over the next half century, Toronto is "going to get increasing numbers of tall buildings."

"Toronto is the leading city in Canada for immigration," Freedman told CTV Toronto. "There's going to be a need for housing, and there's only so many places we know the city wants to accept new housing. So there will be a tendency in the future to want to build up."

Another region that will look markedly different in the next few decades is the waterfront, which will be redeveloped to serve as Toronto's version of New York City's Central Park. Diverse housing mixed with parks and other green space will make Toronto "a whole new city," according to Christopher Glaisek, the vice president of planning and design at Waterfront Toronto.

Experts are also looking at how to feed the people who are expected to fill these new residential developments, a growth spurt that will fuel new and novel ways of mass producing food.

Vertical farming, like having a number of greenhouses stacked one on top of the other, is one such technique. Ideas for the future include a vertical farm on top of the Ontario Food Terminal, which could potentially feed tens of thousands of people. Smaller vertical farms could also be built on top of condominiums to feed the buildings' residents.

But as architects and urban planners talk about density and vertical farming, former mayor David Crombie says input from all of those hundreds of thousands of newcomers is essential for creating a city that all residents want to live in.

"The specifics in the planning will come as the new folks come, and they look around and say, ‘how do we want to make it for us?'" Crombie told CTV Toronto. "I think it's a kind of arrogance to assume that you can figure out a nest for people 50 years from now."

However, the experts agree that the city will grow up, rather than out, in contrast to the post-War baby boom that fuelled the growth of the suburbs.

"The next 50 years is going to be an implosion," says architect Ken Greenberg, the former head of urban design and architecture for the City of Toronto. "The city is going to grow into itself."