Architectural historian of ancient civilizations and engineer; Professor at the Polytechnique (Paris). Choisy was the son of an architect. He studied at the École Polytechnique, Paris, from 1861 to 1863 and from 1863 at the École des Ponts et Chaussées, also in Paris. As part of his education, he traveled to Rome and Athens, beginning in 1866 to study classical architectural elements as many students did. His interest was far more sustained by the structure of these ancient monuments than their decorative detail. Choisy was familiar with Eugène Viollet-le-Duc and his examination of the structure of Gothic architecture. In 1873, Choisy issued L'Art de bâtir chez les romains, a structural analysis of Roman architecture including building materials and the workforce needed to construct it. This approach to architectural explanation led to a second book on the buildings of the Byzantine empire in 1883, and later one on Egypt. Choisy returned to the École des Ponts et Chaussées to teach beginning in 1876. He moved to the École d'Horticulture at Versailles in 1878 (to 1892) adding duties at his other alma mater, École Polytechnique in 1881. Between 1883 and 1894 he published studies on Greek architecture, employing epigraphical evidence, Etudes épigraphiques sur l'architecture grecque. Choisy's magnum opus appeared in 1899, his two-volume Histoire de l'architecture. For this work, he developed single isometric drawings which combined in a single illustration, plan, elevation, section, and a perspective. This appealing graphic distillation was developed in full in his four-volume translation of Vitruvius Pollio's Ten Books on Architecture of 1909. His condensation brought the classic text down four pages of text accompanied by a series of diagrams. Choisy's early architectural analyses described buildings in social and material terms. The appearance of Histoire de l'architecture combined this approach with a historical determinism, a progression of styles set in the context of birth, maturing and decline.
Choisy "interpreted architecture exclusively in terms of the history of construction, demonstrating what he believed to be its essence in a series of grimly clever diagrams. His work is the logical culmination of two centuries of French rationalism and we shall not see its like again." (Watkin) His scholarship was employed by many subsequent architectural historians, including notably, W. R. Lethaby.