Brother-in-law and successor of Hardouin-Mansart, he worked with him on the great projects undertaken in Versailles which he completed in the rocaille style then in vogue.
“The most skilful of our architects” according to Mme de Maintenon, Robert de Cotte had a career as prestigious as that of Hardouin-Mansart. After staying for a long time in the shade of his brilliant brother-in-law, in 1686 de Cotte designed the peristyle of the Grand Trianon by which he intended to prolong beyond the building the perspective of the central walk and the courtyard. Also attributed to him in this palace are the chimney-pieces surmounted by mirrors that replaced the paintings and relief carvings that previously adorned them. This style of chimney-piece became a great success in the 18th century.
On the death of Mansart in 1708, he completed the royal chapel and directed its decoration until the start of the reign of Louis XV. He designed in 1725 the decoration of the Hercules salon, the first major project of the king after his return to Versailles in 1722. It was also under his direction that the rocaille decoration was designed for the bedchamber of the queen (1729) and for the apartments of princes and courtiers in the north and south wings, completed in the first years of the reign of Louis XV.
Rather more so than Hardouin-Mansart, the reputation of Robert de Cotte travelled abroad: German princes and Spanish monarchs turned to him for their residences in Würzburg, Poppelsdorf, Schleissheim, the Buen Retiro in Madrid and in Bonn. He was regarded as the representative of French good taste. The heir to the drawings and plans of Mansart’s architectural practice – they now form the Robert de Cotte Collection in the Bibliothèque Nationale, De Cotte was the worthy continuer of a style initiated by his brother-in-law and which finds its finest example in the place Vendôme in Paris.
Robert de Cotte produced a considerable body of work. More so than Hardouin-Mansart, it covers the whole field of architectural and decorative creation, both civilian and religious. He designed a large number of town houses in Paris (hôtel d’Estrées, du Lude, de Châtillon, etc.). He decorated the choir of Notre-Dame with panelling like in a drawing room (1710s) and designed the façade of the church of Saint-Roch. It was built by his son Jules-Robert in the spirit of Roman baroque (1736-39). Robert de Cotte was also the architect of the splendid buildings of the royal abbey of Saint-Denis (1700-1725).