Dense, organic cities with interconnected building structures and easily accessed common urban spaces. Cities that offer variety, vibrancy and architectural qualities that tempt people to go exploring on foot or by bike. Cities that have a sense of openness, make people feel safe and create opportunities for conversations in public spaces. Cities that are rooted in tradition and a respect for cultural heritage. Cities that provide meeting places in a setting conducive to cultural cohesion. Social and sensory cities. This book points to urban blocks as the structure best suited to pro­moting sustainable building developments and cities. Its first part presents some urban qualities that have evolved from the urban block as a fundamental, flexible element. These examples have been selected from European block cities as well as from old and new urban districts in Copenhagen. The second part of the book outlines the elements of the urban block city and its potential, proposing 10 principles that underpin an action-oriented platform for transforming older urban districts or planning new ones.