This book collects a set of reflections concerning the planning of contemporary cities by urban design, with a special emphasis on some needs and shortcomings emerged during the coronavirus pandemic. With the ultimate goal of designing accessible, inclusive and welcoming green cities, it discusses the urgent need for new systems of public spaces across the city, together with alternative solutions for individual mobility (especially slow mobility) and social interaction. It is intended for a broad readership, including designers, engineers, architects, social scientists, stakeholders, and public administrators, who deal with various aspects of the realization of the City 4.0.