In the midst of our cities, on waste ground between city and landscape, streets of traffic and port or industrial areas, there are some exciting urban spaces: metrozones, the most important potentials for sustainable development. Here, the inner city is suddenly cut off, and the full dynamics of the metropolis and its streams of people and goods can develop—in a unique language of functioning, provision, and distribution. At present, entirely new fields of possibility are opening up in such places, giving rise to innovative, sustainable strategies of urban development: projects that solve the conflicts burdening such districts and generate a new quality of urban space—not suburban idylls, but powerful, lively areas that create a new part of the city within the city. Volume 4 of the METROPOLIS: series illuminates strategies and shows visions for the urban transformation of metrozones in the 21st century.