This scholarly monograph examines the Cathedral of Saint Stephen in Châlons-en-Champagne, tracing its medieval development and its place in French Gothic architecture. Drawing on architectural history, archival evidence, and close analysis of the building’s fabric, Alain Villes situates the cathedral within the religious, urban, and artistic contexts of Champagne. The study addresses the cathedral’s construction history, structural features, decorative programs, and later transformations while clarifying its relationship to broader patterns in medieval church architecture. With extensive documentation, it is intended for researchers, preservation specialists, and readers interested in the history of ecclesiastical buildings in northeastern France.