How do our cities evolve, what forces drive their evolution, and how exactly do they change as a result? Zurich-based architecture firm EM2N has been working on urban transformation processes ever since its establishment in 1997. Initially, the firm's main focus was on the greater Zurich area, yet in recent years they have also developed and realised projects in Berlin, Brussels, and Hamburg. Over time, a diverse body of work has grown, more than half of which consists of conversions of existing buildings, resulting in numerous successes and a few failures, small structures and large-scale complexes, quick decisions and slow processes. What unites the designs, projects, and texts featured in this first monograph on EM2N is a profound interest in the concept of the city as an exciting, contradictory, and above all productive space of human life that the founding partners Mathias Müller and Daniel Niggli have maintained throughout their 25 years of collaboration.In EM2N - City Factory they offer a self-critical review of their achievements and also speak about learning processes, personal interests, and conceptual approaches to future tasks in ever-changing cities. This is supplemented with contributions from fellow architects and friends as well as with a wealth of photographs, plans, drawings, and other illustrations.