In an era of exponential technological change and deepening urban inequality, cities face an existential question: adapt or decline. Innovation Districts by Miquel Barceló offers a bold blueprint for urban transformation, revealing how compact, mixed-use neighborhoods can become engines of creativity, economic vitality, and social cohesion. Drawing on global case studies, from Barcelona's pioneering 22@ District to Boston's Seaport and Medellín's Ruta N, Barceló demonstrates how cities can harness the power of collaboration among universities, startups, corporations, and communities. But success demands more than infrastructure: it requires systemic thinking, inclusive governance, and strategies to prevent gentrification from displacing the very communities innovation should serve. This comprehensive textbook challenges planners, policymakers, and entrepreneurs to move beyond outdated industrial models and embrace the complexity of urban ecosystems. With practical frameworks, systems mapping tools, and insights into smart specialization, Innovation Districts is an essential guide for anyone committed to building resilient, equitable cities that thrive in the knowledge economy. The future of the city starts here.