Pittsburgh would be transformed if it were possible to reconnect downtown with the hill district. The civic arena was part of the problem, creating a dead zone between the two. But also problematic is the I579 cut.
A dream solution would be to cover the roadway and put a park on top or possibly even buildings. An example of this is the Seattle convention center and "Freeway Park". Both are built directly over I5 in the heart of downtown. That neighborhood was transformed from a barren no man's land of noisy traffic to an amazingly pleasant and vibrant place. There are pedestrians crawling all over it and businesses are thriving.
The architecture of the convention center is also striking. It has so many trees and bushes on the roof that it is difficult to figure out what is ground level and what is a patio on top of the convention center. The motif is continued inside with the same plants inside and out, leading to a feeling of being outdoors even when inside.
Having attended a convention there, it immediately triggered a desire for the same thing to be done to a portion of 579 in Pittsburgh. It would connect downtown to the lower hill and allow what we consider "downtown" to grow into the hill district. Currently downtown is an island, separated from everything else by two rivers and a nearly impassible interstate.
I couldn't find good photos of it, perhaps because it blends in so well. But here is a google maps view:
https://www.google.com/maps/@47.6104673,-122.3308259,373m/data=!3m1!1e3
Tack this up as another example of how we could have better spent a half billion dollars than on our tunnel to nowhere.