Hôtel de Salm-Dyck, a private mansion in the 7th arrondissement of Paris

The Hôtel de Salm-Dyck at 97 rue du Bac is a multi-storey stone building with two wings meeting at a curved central bay. The left wing has a grey slate mansard roof with dormer windows; the right wing's tall rectangular windows are flanked by pale shutters and, on upper floors, low black wrought-iron balcony railings. The central bay has large arched windows, and the entrance is a tall black double door with ornate scrollwork panels and a semicircular transom with an oval medallion.

Built in 1722 for Pierre Henry Lemaître, owner of the Château du Marais, possibly by architect François Debias-Aubry, the mansion was sold in 1726 to the maréchale-duchesse de Gramont, née Marie Christine de Noailles, who married her daughter there to the duc de Ruffec, eldest son of Saint-Simon. In 1809 Count Joseph de Salm-Reifferscheidt-Dyck bought it and had the first-floor rooms decorated in the Empire style around 1810 by architect Antoine Vaudoyer and painter Jean-Jacques Lagrenée. It has been a monument historique since 25 May 1982.

The name Salm-Dyck comes from Count Joseph de Salm-Reifferscheidt-Dyck, who bought the mansion in 1809 and was made Prince of Salm in 1816. His wife, Constance de Théis, held a literary salon here. The Empire-style first-floor rooms she used, decorated around 1810 by Antoine Vaudoyer and Jean-Jacques Lagrenée, are listed as monuments historiques.

The Hôtel de Salm-Dyck stands at 97 rue du Bac in the 7th arrondissement; the nearest metro station is Rue du Bac. The building is a private mansion, so the interior is not open as a museum and visits are not offered on a regular basis. The double door with its carved panels and the "JOUR ET NUIT" sign can be seen from the street.

The building was long known as the hôtel de Ségur, after the vicomte de Ségur who owned it at the Revolution. Its name changed with the comte Joseph de Salm-Reifferscheidt-Dyck, who bought it in 1809 and was made prince of Salm in 1816. The two signs beside the door read "97" and "JOUR ET NUIT".