Book excerpt: Urban land is an increasingly precious commodity, particularly in the centers of major cities. Every spare corner of land is in demand, however small, inaccessible, or awkwardly shaped. For architects the challenge is to optimize these sites while simultaneously negotiating the web of planning regulations to create homes suited to today's lifestyles. Infill profiles 39 innovative and imaginative urban dwellings around the world that fill in gaps left bydemolition, or that have been squeezed into plots previously considered unsuitable for development. Each case study is illustrated with photographs, drawings, and specially drawn site plans, all accompanied by authoritative commentary.The authors focus particularly on the challenges that each architect faced and how they were overcome.