The arsenal was the residence of Sully and then Henri IV, who converted it into an apartment. In the 18C, the erudite Marquis of Argenson amassed a collection of books here, enhanced by the Count of Artois. At the Revolution it was expanded further to include the archives from the Bastille. As a result, the Arsenal has been a national library since 1797. It is possible to visit the manuscripts' room, the 18C music salon, and the bedroom and chambers of La Meilleraye (note the 17C paintings).