French architect. He was the most important member of a family of architects active in Paris. His early work included adding a storey to the Hôtel de Sillery (1712) and additions to the Hôtel de Vendôme (1715) in the Rue d'Enfer, but his most significant contribution was the design of two hôtels particuliers in the Faubourg Saint-Germain, the fashionable neighbourhood on the west bank of the Seine. About 1720 he drew up plans for the first of these, the Hôtel de Matignon (in the Rue de Varenne), built 1722-24 for Christian-Louis de Montmorency-Luxembourg, Prince of Tingry. Despite the lack of Classical orders on the exterior elevations of the corps de logis, the overwhelming effect of the Hôtel de Matignon, as observers at the time noted, was closer to that of a palace than an hôtel particulier. During the same period Courtonne also worked on the smaller Hôtel de Noirmoutiers (1722-23) in the Rue de Grenelle, built for Antoine-François de La Trémoille, Duc de Noirmoutiers. Here he organized the rooms around a single central axis. The tripartite arrangement of the garden façade is highly original, with its gentle crescendo of layered surfaces towards the central bay. In 1725 he published the Traité de la perspective pratique. This consisted of an illustrated manual of perspective intended for architects; a discussion of the new trends in Parisian architecture recently put into practice by such contemporaries as Pierre Lassurance I, Germain Boffrand and Robert de Cotte; and plates of his own hôtels, with a discussion of his designs. In 1728 Courtonne became a member of the Académie Royale d'Architecture, lecturing there from 1730. A second treatise, Nouveau essai sur le bon goust en architecture, read before the Académie in 1733, remains in manuscript form. His son, Jean-Baptiste Courtonne was a painter and architect and built the château of Villarceaux (Val-d'Oise) in 1758. //