This section provides an overview of the distinctly different urban forms of five cities: Istanbul, Johannesburg, London, Mumbai, and Tokyo. Satellite photographs illustrate the diversity and complexity of human impact on these cities, as physically manifest in street widths, block and plot sizes and distribution of open green spaces.
All five cities contain centrally-planned zones, but each also contains areas that have grown informally and organically. These physical structures have arisen to accommodate each citys geographical and environmental conditions, (rivers, coastlines, mountains, orientation, etc), as well as its cultural, social and economic systems. Urban form – the DNA of the city – bears the imprint of the flows and forces that shape our daily lives.
Given the complex and locally specific relationships between urban form and city life, architects and city planners face many challenges in trying to bring about positive change within cities of this size and history. These include the task of providing adequate infrastructure for the large number of informal settlements that have arisen in cities like Mumbai; protecting Tokyo from multiple potential natural disasters; and filling in the large areas that are Londons legacy from redundant infrastructure and industries. Many cities are being assailed by homogeneous, globalised international models which take no account of their particular, individual structures. The lasting success of planning policies and future developments may depend on the sensitivity of such interventions within the grain of their urban DNA.