A detailed analysis of the architectural theories and projects that contributed to the construction of cities and landscapes in the 20th century reveals two opposing tensions: on the one hand, the choice to support the economic exploitation of natural resources; on the other hand, the refusal to do so in the name of an early ecological awareness. These two tendencies not only manifested themselves as contrasts between different professional groups and cultural movements, but even as sometimes indistinguishable parts of the biography of the same author. In the face of these ambivalences, excavating the vestiges of modernity is now more necessary than ever to reinvest the capital that architectural theories and projects have accumulated along the complex path of industrial society.