What remains of Horta's Art Nouveau, apart from his style and typical plant-related vocabulary? Horta and the Grammar of Art Nouveau offers an innovative analysis of the architectural approach of Victor Horta, the Belgian architect whose creations between 1893 and 1905 were seminal for the development of Art Nouveau architecture. The first part of the book sheds a new light on the toolbox of Victor Horta by focusing on the architectural sources of one specific work, the Tassel house. It gives an insight into where and how Horta conceived his designs. The second part discusses fundamental themes of Horta's architecture, such as the rhetorical use of structure, the innovative use of materials, and the use of light in the development of the dynamic plan. The third part explores the relation between Horta's invention of Art Nouveau and the colonial enterprise of King Leopold II. This publication is illustrated with maps, plans, and unpublished photographic material commissioned by Victor Horta. Distributed for Mercatorfonds Exhibition Schedule: Bozar, Brussels (October 2023–January 2024)