Cities are complex systems connected to economic, ecological, and demographic conditions and change. They are also characterized by diverging perceptions and interests of citizens and stakeholders. Thus, in the arena of urban planning, we are in need of approaches that are able to cope not only with urban complexity but also allow for participatory and collaborative processes to empower citizens. This to create democratic cities. Connected to the field of smart cities and citizens, we present in this paper, the prototype of an urban digital twin for the 30,000-people town of Herrenberg in Germany. Urban digital twins are sophisticated data models allowing for collaborative processes. The herein presented prototype comprises (1) a 3D model of the built environment, (2) a street network model using the theory and method of space syntax, (3) an urban mobility simulation, (4) a wind flow simulation, and (5) a number of empirical quantitative and qualitative data using volunteered geographic information (VGI). In addition, the urban digital twin was implemented in a visualization platform for virtual reality and was presented to the general public during diverse public participatory processes, as well as in the framework of the “Morgenstadt Werkstatt” (Tomorrow’s Cities Workshop). The results of a survey indicated that this method and technology could significantly aid in participatory and collaborative processes. Further understanding of how urban digital twins support urban planners, urban designers, and the general public as a collaboration and communication tool and for decision support allows us to be more intentional when creating smart cities and sustainable cities with the help of digital twins. We conclude the paper with a discussion of the presented results and further research directions.

Bill Hillier’s space syntax method and theory enables us to describe the spatial properties of a sustainable city. Empirical testing of the space syntax method over time has confirmed the capacity and innovativeness of analyzing spatial relationships with the purpose of understanding and explaining the socio-spatial organization of built environments. However, the conceptual framework of space syntax elements is scattered around in various academic writings. This article, therefore, gives a holistic and compact overview of the various concepts that are used in space syntax, from its basic elements to various analytical techniques and theories. To achieve this compact overview, we reviewed all space syntax literature accessible since the 1970s for finding core references to various concepts used in space syntax. Following a short description of its foundation and evolution through the work of Bill Hillier, we explain its basic concepts and measures in the form of an extended glossary. Explanations are enriched with various space syntax analyses and scenario testing on various scales that were applied to the city of Rotterdam in the Netherlands. We conclude with a discussion about the advantages and limitations of space syntax and about how this method adds value to the creation of sustainable cities.

This open access textbook is a comprehensive introduction to space syntax method and theory for graduate students and researchers. It provides a step-by-step approach for its application in urban planning and design. This textbook aims to increase the accessibility of the space syntax method for the first time to all graduate students and researchers who are dealing with the built environment, such as those in the field of architecture, urban design and planning, urban sociology, urban geography, archaeology, road engineering, and environmental psychology. Taking a didactical approach, the authors have structured each chapter to explain key concepts and show practical examples followed by underlying theory and provided exercises to facilitate learning in each chapter. The textbook gradually eases the reader into the fundamental concepts and leads them towards complex theories and applications. In summary, the general competencies gain after reading this book are: – to understand, explain, and discuss space syntax as a method and theory; – be capable of undertaking various space syntax analyses such as axial analysis, segment analysis, point depth analysis, or visibility analysis; – be able to apply space syntax for urban research and design practice; – be able to interpret and evaluate space syntax analysis results and embed these in a wider context; – be capable of producing new original work using space syntax. This holistic textbook functions as compulsory literature for spatial analysis courses where space syntax is part of the methods taught. Likewise, this space syntax book is useful for graduate students and researchers who want to do self-study. Furthermore, the book provides readers with the fundamental knowledge to understand and critically reflect on existing literature using space syntax.

The burgeoning landscape of literature on mobility inequalities has led to discrepancies between a conceptual understanding of mobility inequalities and its implementation in planning practice. Reviewing 270 publications across five decades, this article identifies intrinsic and extrinsic factors and approaches for understanding and analyzing mobility inequality. Using two thought experiments to critically locate variations in factors and approaches, dilemmas and challenges in addressing mobility inequality for the marginalized are exposed. The article concludes with future research directions for investigating mobility inequality.

The global trend towards the growth of urban population poses the issue of the public space influence on outdoor practices of different subjects. Urban public space is the carrier of an ever-increasing number and density of users. Walking, both as a form of transportation and as a vector to physical activity and social interactions, emerges as a fundamental category of behaviour. The proposed research develops a theoretical and methodological framework for assessing walkability of the urban space. Building on concepts of capability and affordance, walkability is herein conceptualized in terms of the effect of affordances incorporated into the built environment on individuals’ propensity to walk for different purposes. The methodological framework aims to capture the characteristics of walkability across scales as the product of the intrinsic and extrinsic properties of an urban setting.