I lived in Germany for two years without a car. The public transportation there was amazing—I learned to appreciate how little I needed a car, provided the infrastructure was good enough/I had a bike. In many cities there's a "Fußgängerzone": pedestrian-only areas; these were mostly found in the city center where the streets and shops are too dense to allow much traffic. I remember specifically in Frankfurt am Main a…
This was tried some places in the US in the part. Unfortunately most times they failed. Unable to attract enough people, they felt even less alive than the streets and entered a cycle a of death. However there are some signs of a rebirth: https://www.researchgate.net/publication/275887405_American_...
To really make it work, the area has to be accessible to walking (and public transport). Which usually means higher population densities than most US cities -- even major cities -- have, and better public transit.