Modernism is the most defining architectural expression of the 20th century – a movement that transformed built environments around the world in an unprecedented way. Many of these buildings are in need of repair now or their original function is no longer needed. This publication in cooperation with Docomomo explores strategies of rehabilitating works of this era. Architects and art historians discuss challenges in the preservation of Modernist buildings. 24 best-practice examples are highlighted, illustrating various approaches to restoration. Among them, there are unknown gems such as the Calouste Gulbenkian Foundation in Lisbon or the stunning house that Juan O'Gorman built for his father in Mexico – interventions guided by respect for the authenticity of the architecture and based on substantial research.