The world is not flat; cities are more important than ever before. We observe an increased competition between cities to attract, create, and retain talents and innovative companies. For urban leaders, the capacity to innovate is central to urban competitiveness. One of the recent trends in local economic development is the concept of innovation districts. The toolkit analyzes the re-emergence of downtown areas, the importance of innovation for urban competitiveness, the recipe for designing a successful innovation district, and provides an innovation district's framework - urban, productive, collaborative, and creative - to accelerate cities' innovative capacity.With case-studies from 22@ Barcelona, Boston's Innovation District, and one-north Singapore, the book will give clear guidelines to urban leaders on how to activate a successful innovative ecosystem. The book will be of interest for urban planners, local development agencies, urban policymakers, urban theorists, and anyone with a strong desire to make cities more innovative and more interesting.