Young Robert finished his studies with the Jesuits at the Collège de Navarre in 1751 and entered the atelier of the sculptor Michel-Ange Slodtz who taught him design and perspective but encouraged him to turn to painting.

In 1754 he left for Rome in the train of Étienne-François de Choiseul, son of his father's employer, who had been named French ambassador and would become a Secretary of State for Foreign Affairs to Louis XV in 1758.

[2] He worked for a time in the studio of Giovanni Paolo Panini, whose influence can be seen in the Vue imaginaire de la galerie du Louvre en ruine (illustration).

[6] Robert's first exhibition at the Salon of 1767, consisting of thirteen paintings and a number of drawings, prompted Denis Diderot to write: "The ideas which the ruins awake in me are grand."

Equally at ease painting small easel pictures or huge decorations, he worked quickly using an alla prima technique.

[2] Enterprising and prolific, Robert also acted in a role similar to that of a modern-day art director, conceptualizing fashionably dilapidated gardens for several aristocratic clients, summarized by his possible intervention at Ermenonville; there he would have been working with the architect Jean-Marie Morel for the marquis de Girardin, who was the author of Compositions des paysages (1777) and had distinct views of his own.

In 1786 he began his better documented[14] collaboration at Méréville, with his most significant patron, the financier Jean-Joseph de Laborde, who found François-Joseph Bélanger's plans too expensive and perhaps too formal.

Robert's contribution to garden design was not in making practical ground plans for improvements but in providing atmospheric inspiration for the proposed effect.

[19] Robert's commissioned painting of the long-delayed rejuvenation of the park at Versailles, begun in 1774 with the cutting down of the trees for sale as firewood, is a record of the event, resonant with allegorical meaning.