How heavy is a city? To ask this today means to intercept the emerging figure of the technosphere and its staggering planetary magnitude. The contemporary city scatters in all directions. It is a vast and growing system propelled by the combustive dynamics of fossil fuels. It is an offshoot of the biosphere, made up of all its 8.2 x 10⁹ human constituents, and all that keeps us alive, including domesticated animals and plants, fisheries, plantations, farmland, infrastructure, institutions, energy supplies, global transportation systems, and nature reserves. It is a city enmeshed within a multiplicity of other species' cities. To ask how heavy a city is, is also to sketch a coalition between different knowledges, bringing together thinkers, activists, poets, artists, historians, Earth scientists, philosophers, architects, and cyberneticians. This book is an insight into the multiple convergences necessary to think with others and renew the most beautiful word for cohabitation: city. This book, dedicated to the themes of the 7th Lisbon Triennale, brings together an international group of thinkers, practitioners, artists, and activists who build on existing perspectives to propose new, unbounded, transformative ones. With a foreword by José Mateus, and texts by Michaela Büsse, Emanuele Coccia, Kate Crawford, Paul N. Edwards, Peter K. Haff, Bruno Latour, Tim Lenton, Geoff Manaugh, José-Carlos Mariátegui, Michael Marder, Anne McClintock, Raqs Media Collective, Lívia Nolasco-Rószás, Andrew Pickering, Ann-Sofi Rönnskog and John Palmesino, Soundwalk Collective and Patti Smith, John Tresch, Laura Tripaldi, Jan Zalasiewicz and Mark Williams, et al.