His neoclassic orientation was established from his early studies with the prophet of neoclassicism Giovanni Niccolò Servandoni and with the radical classicist Étienne-Louis Boullée in Paris and through his Prix de Rome sojourn as a pensionnaire of the French Academy in Rome. His time in Rome coincided with a fervent new interest in Classicism among the young Frenchpensionnaires, under the influences of Piranesi and the publications of Winckelmann. Returning to Paris, he was quickly given an appointment as an inspector of public works for the city of Paris, under the architect Pierre-Louis Moreau-Desproux, whose own time at the French Academy in Rome had predisposed him to the new style. In this official capacity he oversaw the construction of Ange-Jacques Gabriel's Hôtel Saint-Florentin in the rue Saint-Florentin, where Chalgrin was able to design the neoclassical gateway to the cour d'honneur. In 1764 he presented his uncompromisingly neoclassical plans for the Church of St. Philippe-du-Roule ; its colossal Ionic order of columns, which separated the barrel-vaulted nave from the lower, barrel-vaulted aisles, was carried around the apse without a break. In this church, which was built 1772-84, he revived a basilica plan that had not been characteristic of French ecclesiastical architecture since the sixteenth century. In 1775 he was appointed First Architect to the comte de Provence, brother of Louis XVI; he designed the pavilion of the comtesse de Provence at Versailles. In 1779 he was appointed overseer of the building projects of another brother of the king, the comte d'Artois. In 1777 Chalgrin partly remodelled the interior of Church of Saint-Sulpice, which had been given a thoroughly neoclassical façade by Chalgrin's former master Servandoni over forty years before. He also designed the case for the great organ. Towards the end of the French Revolution in 1798 Chalgrin threw up the buildings for the first Exposition des produits de l'industrie française, with an extremely tight deadline. A large circle of porticos surrounded a Temple of Industry that would hold the objects of industries that the jury had selected. After the Revolution Chalgrin extended the Collège de France and made alterations in the Palais du Luxembourg to suit it to its new use as the seat of the Directoire. The Arc de Triomphe was commissioned by Napoleon to commemorate the victorious armies of the Empire. The project was under way when Chalgrin died, and it was completed by Jean-Nicolas Huyot. Chalgrin married Émilie, a daughter of the painter Joseph Vernet. They had one son.
Major works
1767–1769: Hôtel Saint-Florentin, for the comte de Saint-Florentin ; demolished 1842.
1767–1770: Hôtel de Mademoiselle de Luzy
1774–1780: Additions to the Collège de France
finished 1775: Construction of Claude Nicolas Ledoux's designs for dwellings at Versailles for Madame du Barry and the comtesse de Provence
