Self-taught, he devoted himself to saving France's historic monuments, sculptures and tombs from the ravages of the French Revolution, notably those of Saint-Denis and Sainte-Geneviève.

Thanks to support from Jean Sylvain Bailly, Alexandre Lenoir successfully demanded that all art objects from state properties be gathered together in this museum.

These objects were confiscated at different religious houses and stored in a single place to avoid their dispersal and destruction.

He struggled against revolutionary vandalism and managed to save statues and loot which he stored at the couvent des Petits-Augustins.

In October 1796, Lenoir was among a number of artists who signed a petition supporting plans to seize works of art from Rome, in response to an early artists' petition orchestrated by Quatremère de Quincy that remonstrated against these plans.