Frankfurt, Germany turned much of the old fortified city into a pedestrian priority realm. It adapted its inherited organic street network to the car and rail by applying the Fused Grid model (see Wikipedia).
A twinned perimeter road (red) frames the central district, which is about 900 m wide by 1500 m long, the dimensions of a walkable area. Feeder roads (blue) serve the distinct but do not go through directly, particularly in the North-South direction. Pedestrian-only streets (green) dominate the area making the city centre, all its services and amenities accessible on foot ; a true pedestrian haven, free of traffic noise, fumes, risk and obstruction, a delight to experience and an example to emulate in old and new districts.
The streets below have been returned to their rightful owners, the pedestrians, and thus have re-established the tru meaning of “the public realm”.