In the early 1830s, a movement for the restoration of medieval buildings appeared in France. Viollet-le-Duc, returning from a study trip to Italy, was ordered by Prosper Merimée to restore Vezelay abbey. This work marked the beginning of a long series of restorations.
Among his restorations:
- Churches :
- Town Halls :
- Castles :
- Fortified city of Carcassonne
- Château de Coucy
Some of his restorations, such as that of the castle of Pierrefonds, were highly controversial because they did not aim so much at accurately recreating a historical situation as much as at creating a "perfect building" of medieval style.
Throughout his career he also kept taking notes and drawings, not only on the buildings he was working on, but also on Romanesque, Gothic and Renaissance buildings that were to be soon demolished. His study of medieval and Renaissance periods was not limited to architecture, but extended to furniture, clothing, musical instruments, armament ...
All this work was published, first in serial, and then as full-scale books, as:
- the Dictionary of French Architecture from 11th to 16th Century (1854-1868) (Dictionnaire raisonné de l'architecture française du XIe au XVIe siècle)
- the Dictionary of French Furnishings (1858-1870) (Dictionnaire raisonné du mobilier français de l'époque Carolingienne à la Renaissance.)
- Viollet-le-Duc systematized his approach to architecture and architectural education in the Entretiens sur l'architecture (in 2 volumes, 185872), Discourses on Architecture.