Main Street ain’t what it used to be. Will the shopping cart become obsolete? Not quite—but smart brick-and-mortar stores are undergoing a major transformation to keep up with the times.

Our cities' parking lots are in the midst of a serious makeover. From smart garages to social parking spots, this is the future of urban parking.

Around the world, cities are getting savvier about fighting back against air pollution — and we're profiling the tech, apps, and other tools that'll have you breathing easier.

Livin' large is great, but growing megacities are creating unprecedented urban challenges. We delve into the difficulties faced by growing metropolises — and uncover some bright sides, too.

From wearable air-quality trackers to upcycled phone booths, these cool urban innovations are changing our cities for the better.

Here to save the world: these incredible teenagers from around the world, who've submitted genius-level projects to the Google Science Fair.