Now the successors of those who helped build the Cogswell interchange more than four decades ago want to tear it down, leaving behind 6.5 hectares that could be redeveloped to repair the fractured heart of the city.
"What we have here is an incredible opportunity," says Andy Fillmore, a veteran city planner and Halifax's former manager of urban design.
Fillmore is among those trying to come up with a plan for the massive hole that would remain in downtown Halifax if the concrete comes down.
It's a priority for the Strategic Urban Partnership, an organization comprised of public and private organizations that Fillmore helped found with the goal of revitalizing Halifax's urban core.
"We can do that thing that other cities sit around their boardroom tables and say, 'Did you see what Halifax did? Can you believe that amazing thing they did?' " says Fillmore.
"I think that's the promise that Cogswell holds."
The deteriorating jumble of overpasses and underpasses occupies a large swath of land near the waterfront where the city's north and south ends meet. The south is known for its universities and high-end properties, while the north end is occupied mainly by the working class and industrial properties including the shipyard.
Cogswell's imposing, pretzel-like design cuts across Barrington Street, a main artery that spans nearly the entire length of the Halifax peninsula, effectively separating both ends of the city.
The interchange has been criticized for being too big. And without sidewalks, it's not pedestrian friendly.
The structure was built in 1970 at a cost of $5.8 million in the name of urban renewal — an effort to rejuvenate what were considered decaying inner cities. A neighbourhood was lost and more than 100 buildings demolished to make room for the interchange.
At the time, developers envisioned the interchange feeding into a multi-lane expressway that would cut through downtown Halifax and its historic properties, right along the waterfront.
Alan Ruffman, a local historian, was among those leading the charge to stop what was to be known as Harbour Drive.
"It's hard to believe, but that's the thinking in those days," says Ruffman.
"This was the time when Toronto had built the Gardiner Expressway, it was wanting to build the Spadina expressway. Other towns like Fredericton built a fairly sizable road along their river.
"Expressways were believed to be the way to move traffic and we were in the game."
But it wasn't meant to be. Plans for the expressway eventually fell through amid a lack of funding and public dissent, and Halifax was left with an orphaned interchange.
For Mike Savage, the former Liberal MP turned mayor of Halifax, tearing down the interchange, dubbed locally as the Road to Nowhere, will be a chance to right a historic wrong.
"It's a relic of a different time, an outdated idea of cities," says Savage, who took over as mayor last fall.
"When I look at that space and think about what could happen, I'm less thinking about a specific purpose but a broader idea of what it could mean for Halifax."
No redevelopment plan has been accepted and there's no time frame yet for the project, but Savage says he'd like to see work on the site begin during his four-year mayoral term.
"Getting it right is really important," he says.
As for what the space could look like, those involved say public input will be key. The Strategic Urban Partnership will host a public meeting May 16 called the Cogswell Shakeup where residents will be able to float ideas for the site.
So far, suggestions range from more bike lanes to an aquarium to a stadium, though both Savage and Fillmore say housing catering to a range of incomes is a priority.
Ruffman says he'd like to see a plan that harkens back to Halifax's past — small building lots, narrow streets and affordable housing for people who work downtown that would benefit the city's entire core.
"The interchange is part of a number of other opportunities," he says. "It's a case of Halifax deciding that we don't want to be an aluminum and granite city (like) Calgary has become downtown."
Fillmore is wistful when he speaks of the possibilities for Cogswell.
While changes might be years down the road, he's just thankful the city has a second chance to get it right, an opportunity Fillmore doesn't believe would be possible if the waterfront expressway had been built.
"It would have put us beyond the point of no return," he says.
"We're lucky that we just have one little piece of it that's in our means to manage."