Hôtel Thiroux de Lailly, A private mansion in the 3rd arrondissement of Paris

Hôtel Thiroux de Lailly is a private mansion in the Marais district of the 3rd arrondissement, built between 1739 and 1741 after designs by architect Michel Tannevot. The façade displays Louis XV style with a triangular pediment, ornate windows, rocaille scrollwork, and stone masks beneath the window ledges.

A previous mansion on the site belonged to the Montmorency family until 1632; Nicolas Fouquet and his second wife Marie-Madeleine de Castille lived there from 1651 to 1658, and the writer Théophile de Viau also stayed. Jean-Louis Thiroux de Lailly, a postal farmer, bought it in 1727 and had architect Michel Tannevot and master mason Jean-Pierre Langiboust rebuild it in 1739–1741. The state bought it in 1951 and installed the École nationale des impôts, which remained until 2001.

The house takes its name from Jean-Louis Thiroux de Lailly, a fermier des Postes who bought it in 1727 and had it rebuilt from 1739 to 1741. Its nickname, hôtel de Montmorency, recalls the noble family that owned the earlier building on the site until 1632. The writer Théophile de Viau lived in that predecessor, and Nicolas Fouquet stayed there with his second wife between 1651 and 1658.

The building is located at 5 rue de Montmorency in the Marais and is within walking distance of the Rambuteau metro station. Since the building is currently used by the French government, visits are restricted to guided tours, so check ahead before planning your visit.

The carved woodwork by Nicolas Pineau (1684–1754) was later moved to Waddesdon Manor in England for the Rothschild family. In the garden, a neoclassical fountain also carved by Pineau can still be seen. The building covers 2,053 square metres.