The completion of the cour carrée was begun during the reign of the sun king, Louis XIV, only to be abruptly abandoned, as the royal court moved to Versailles.
Some of the facades were partially completed, but the wings were mostly empty shells, and some were not even roofed. Not until Napoleon I were the works initiated during this time actually finished, 150 years after they were begun.
Even during the course of construction, development proceeded in fits and starts. Officially the royal architect was Louis le Vau, and as such he was the natural successor to Lemercier. However, none of the work by le Vau has been allowed to leave its individual mark.
The prestigious outer façade of the eastern wing was designed by committee, of which le Vau was member. However, the design has generally been accredited to Claude Perrault. This is significant for several reasons, because le Vau initially began his work by following the pattern set by Lescot and Lemercier. Perrault’s project, on the other hand, broke with that pattern. What is more, it was the design principle of Perrault that was adopted at the end of the day, not only for the eastern wing but also the southern and northern wings. The work by le Vau on these wings was, thereby, largely obliterated. It is Perrault’s facades, completed by Napoleon’s architects Percier and Fontaine that we see today.
That being said, the Seine was briefly dominated by the ideas of Louis le Vau. The Collège des Quatre Nations, now l'Institut Français, is perhaps his finest achievement, and faces the Louvre directly from across the Seine over the pedestrian bridge le Pont des Arts. Before Perrault’s work was allowed to supersede his, the façade of the institute stood opposite the Louvre façade completed by le Vau from across the river.
As Lemercier had done with outer façade of the western wing, le Vau placed a domed pavilion at the centre. He then completed the wing, exactly as Lemercier had, by copying the facades of Lescot. To maintain symmetry, he had little choice as Lescot had already built the south-facing Pavillon du Roi and the western portion of the wing.
However, there was one respect in which he did differ from Lescot and Lemercier. Unlike the central pavilion of Lemercier’s west-facing outer façade, which was quite plain (The ostentatious décor of pavilion, today named Sully, facing the Cour de Napoleon is the result of later modifications by the architects of Napoleon III, Lefuel and Visconti), le Vau placed double-ordered engaged corinthian columns across the ground and first floors. These were topped by statues in the manner often employed by le Vau elsewhere, such as at the garden front of Vaux-le-vicomte. The attic floor and the dome rose above in much the same way as Lemercier’s dome.
In introducing orders on the Louvre’s outer façade, le Vau established a new precedent. It seems safe to assume that the purpose was to tie the façade of the institute from across the river to that of the Louvre, as a piece of concerted urban planning. We know that le Vau planned a bridge to link the two, though the current bridge has nothing to do with him.
Le Vau also completed the courtyard façades of the southern wing and built both the outer and inner facades of the northern wing and the inner façade of the eastern wing. However, in this le Vau simply copied Lescot and Lemercier, and the attic floors were later removed to fit with the hidden roofline of Perrault’s new wings. Initially, that solution was begun on the eastern wing but was extended to both the north and south wings by Napoleon. As for the central pavilion facing Rue de Rivoli to the north, it was begun by Perrault and completed by Percier and Fontaine.
Le Vau also made substantial changes to the Tuileries palace, which was linked to the Louvre by the grande galerie, built under Henri IV. The palace was burnt to the ground after the fall of Napoleon III. He also enlarged the petite galerie following a destructive fire there.