In a stunning reversal, Sidewalk Labs has abandoned plans to develop a smart city in Toronto, citing uncertainty in the Toronto real estate market and the global economy. 

“It has become too difficult to make the 12-acre project financially viable without sacrificing core parts of the plan we had developed together with Waterfront Toronto to build a truly inclusive, sustainable community,” said Dan Doctoroff, CEO of the Google sister company, in an open letter published Thursday. 

Sidewalk Labs said it informed Waterfront Toronto of the decision yesterday. 

The decision ends a controversial three-year partnership between Sidewalk Labs and Waterfront Toronto, the organization overseeing the project. The proposed development would have seen the Quayside neighbourhood—former industrial lands between Toronto’s lakeshore and its downtown core—transformed into a high-tech, low-carbon district.  

Here’s what you need to know.