The sequel to the authors' Are We Human?, this provocative book is an urgent manifesto for an alternative architectural philosophy. It treats bacteria as the real architects, construction workers, maintenance crews and inhabitants of buildings. Colomina and Wigley draw on the latest research into microbes to rethink the past and possible futures of the built environment. The book explores the intimate entanglements of the microbes within bodies and buildings over the last 10,000 years, culminating in the antibiotic philosophy of contemporary architecture. The diseases of our time are diseases of the built environment. The deadly combination of rapidly declining microbial diversity and rising antibiotic-resistant bacteria is as great a threat as climate change. Hostility to bacteria has to give way to new forms of hospitality from a more symbiotic architecture that learns from bacteria, embracing them and reconnecting with soil, plants and other species. Buildings based on fear of bacteria, which is to say fear of life itself, must give way to buildings learning from models of coexistence based on bacteria themselves.The main goal of the book is to rethink the very idea of shelter in terms of forms of inclusion rather than prophylactic forms of exclusion.