Le Corbusier's buildings and writings are widely considered the most important testimony of twentieth-century architecture. No estimate of his genius and influence can be made without reference to the sketchbooks that he carried with him nearly everywhere throughout his life. He jotted down everything that caught his interest—buildings, people, pictures, ideas, projects, objects. When pondering a new project, Le Corbusier often referred to these notations, even those made years before. The travel sketchbooks were a perennial source of stimulation to his imagination. Le Corbusier carefully preserved these documents and selected a special group of them for eventual publication. His heirs, the Fondation Le Corbusierin Paris, have zealously protected them; but for two decades they have been available only to those scholars able to examine them in the Paris vault. Now, however, the Architectural History Foundation and The MIT Press have jointly undertaken to publish all seventy-three sketchbooks selected by the master in a series of four volumes, of which this is the first. The publication has been edited by a committee of Le Corbusier scholars—Timothy Benton, H. Allan Brooks, Bal Krishna V. Doshi, Norma Evenson, Stanislaus von Moos, Francesco Passanti, Madhu Sarin, Peter Serenyi, and Jerzy Soltan. This first volume, covering the period 1914-1948, includes drawings from the architect's training, notes on his life in Paris and his first recorded thoughts and subsequent ideas on city planning, sketches from a Zeppelin trip to South America, his own critique of his Villa Savoie, the conception of the Unite d'habitation for Marseilles, writings on his Pessac housing project, the evolution of the Voisin Plan, and his evaluation of Villa Mandrot, often cited as the turning point in his architectural style.