Some time ago, Walter Benjamin and Asja Lacis used the term "porosity" with reference to Naples' urban characteristics - spaces merging into each other and providing the backdrop for the unforeseen - improvisation as a way of life. Today, the term "porosity" in this context is increasingly used conceptually. Well-known authors from the worlds of architecture, town planning, and landscape design embark on a search for new concepts for a life-enhancing, user-friendly city - with reference to this enigmatic term. The term refers to the overlaying and interweaving of spaces and structures, to urban textures and their architectural properties and qualities - to cities with radically mixed urban functions.

Architektur ist die Kunst, Raume zu artikulieren. Auch fur den Massstab der Stadt, von der Turschwelle bis zur Region, geht es um die Architektur urbaner Raume. Diese sind Gegenstand des architektonischen Entwurfs, der ein Repertoire spezifischer Mittel schoepferisch einsetzt, so dass wir Stadte als raumlich gestaltet erleben. Dieses architektonische Repertoire wird hier beschrieben. Entwurf und urban design finden wieder Eingang in die Urbanistik.

Architecture creates complex spatial situations that are the subject of urban design. Design uses a repertoire of specific architectural means in a creative way, resulting in cities that can be lived in and perceived in their three-dimensional experience. The current book, an extended new edition of Architecture of the City (2016), describes the repertoire with which architecture and design regain an entry to urbanistics. It pleads for an "architectonic turn" in urbanistics - a demand to finally comprehend the city architecturally: the issue is not just about buildings in the city, but about architecture of the city as a whole, as is clearly expressed in the new title of City as Architecture.

The question of composition and spatial qualities arises in every urban design concept or intervention in the spatial structure of urban public squares. How are the essential elements involved: dimension, proportion, alignment, cohesion, accesses, shaping of focus point and of edges like surfaces and materials? How do they contribute to a character of urban space with which residents can identify? Comparing historical examples with current designs aids one in visualizing spatial effect. Similar to a floor planmanualfor buildings,Platzatlas allows the user to evaluate spatial conditions for movement and rest based on comparable existing urban squares. The book offers the planner a comparative example for most conditions (shape, size, location, topography, and so on). Seventy European urban squares are presented and explained with the most important characteristics in a consistent manner in as-built plan, ground plan, section, and axonometric projection.