The crumbling foundry ruins and clothing-factory remnants of west Galt are being fitted for a $120-million makeover.

Designs for the massive Hip Developments project, unveiled to politicians and the public in the packed atrium of the Dunfield Theatre on Thursday, might even hit $125-million by the time it is completed in 2020.

Yes, “The Gaslight District” will be big. Really big.

“It’s probably the biggest private commercial-residential development in the city ever,” said Greg Durocher, president of the Cambridge Chamber of Commerce.

“This is an amazing investment in the prosperity of this community. This is going to be a game-changer in downtown Galt.”

Why a game-changer? Because, Durocher explained, it will bring young people — yearning for an urban atmosphere — here to live. They’ll also shop and dine and catch a play at three-year-old Dunfield, a cosy 500-seater built for $14-million.

Two 20-storey towers, with about 14 floors of residential units apiece, will stand over a reimagined historic South Works hub of fine restaurants, a central courtyard and a boutique marketplace striving for a 19th-century feel and texture.

Four-hundred residential units are planned, once the towers successfully pass through the city planning process.

High-tech office jobs are another feature. That’s the Gaslight vision city staff have helped the developer cobble and refine over the last 18 months.

An innovative tech hub and office environment will fill an old Tiger Brand outpost. Conestoga College students will learn about advanced manufacturing and cybersecurity in the Grand Innovations centre for applied research. Maybe 100 students a year will go there. It may start small but it will grow, college president John Tibbits believes.

“This is a breakthrough for us,” Tibbits said.

“We see this as a start. We see ourselves becoming a bigger player in advanced research and applied research in this community, but also in Canada.”

A place to work, live, study, create: That is the sales pitch from Hip, a division of Melloul Blamey Construction.

Plus a west-side place to walk across the river to. The $1 million pedestrian bridge the city will soon build across the Grand River will connect into a sculpture garden at Gaslight’s heart. The so-called “bridge to nowhere” — recently a baffling symbol of fiscal incoherence to city critics — now has a destination.

“That’s the bridge to somewhere now,” Hip president Scott Higgins said.

So the east side shops of the Grand River will connect to the west side by a foot bridge with a stunning middle-of-the-river view and no cars to dodge or exhaust to inhale.

The new $13-million digital library going in at the historic old post office will have a shoe-leather link to the Gaslight community.

Suddenly, dots are being connected. Or so it seems now that Gaslight appears a go.

This is big news, Cambridge Mayor Doug Craig said.

It’s he biggest announcement, in his opinion, since Toyota promised in 1985 to plunk its initial $400-million car plant on Fountain Street.

“It’s going to transform the community, much like Toyota did in terms of employment and jobs and so on,” Craig predicted. “It is certainly going to have a very positive impact in enhancing the heritage of the city and our belief in the river system in our community.”

Gaslight aims to be a tribute to Cambridge’s industrial past, not a trashing of it.

The “lion’s share” of the remaining historic industrial properties are to be preserved but there will some proposed “selective demolition” to make room for the towers and open up the courtyard.

“No one goes in with sledgehammers and just goes at it,” Higgins said. “It’s all very engineered.”

And good chunk of the work, depending on the fate and pace of approvals and permits, could begin by next summer.

The $120-million investment looms large for Galt’s long-sought renaissance. But the Gaslight project will turn a few dozen current tenants of the South Works outlet mall into displaced retail vagabonds.

Hip is purchasing the outlet mall from longtime owner John Wright. The deal closes in June. Current tenants can stay for the Christmas business season, but will have to leave during the two-year redevelopment. They might find homes elsewhere in Cambridge’s three core areas. They might have a chance to return to the completed Gaslight.

“There’s certainly an opportunity to come back,” Higgins said.

But there may be no turning back for Galt, and Cambridge, once Gaslight is realized.

“This is all of a sudden going to shine a light on downtown Galt,” Durocher said.