As in many American cities, large highways slice through downtown Dallas. Sidewalks seem intermittent, parking lots abundant, and locals respond with strange looks when asked the best way to walk to a nearby bar or restaurant.

But Dallas is pouring millions of dollars into changing all that. In the past decade, the city has quietly inserted a handful of small green gardens between downtown office towers and condos, providing small reprieves from the expanses of asphalt and concrete. As part of this initiative, over ten years ago, local civic leaders began talking to a team of designers and engineers about coming up with a scheme for uniting the city's fractured downtown by covering over an existing freeway with a park.