The Bibliothèque nationale de France (BnF) operates public libraries in Paris, among them the François Mitterrand Library, Richelieu Library, Louvois, Opéra Library, and Arsenal Library. There are three public libraries in the 4th arrondissement. The Forney Library, in the Marais district, is dedicated to the decorative arts; the Arsenal Library occupies a former military building, and has a large collection on French literature; and the Bibliothèque historique de la ville de Paris, also in Le Marais, contains the Paris historical research service. The Sainte-Geneviève Library is in 5th arrondissement; designed by Henri Labrouste and built in the mid-1800s, it contains a rare book and manuscript division. Bibliothèque Mazarine, in the 6th arrondissement, is the oldest public library in France. The Médiathèque Musicale Mahler in the 8th arrondissement opened in 1986 and contains collections related to music. The François Mitterrand Library (nicknamed Très Grande Bibliothèque) in the 13th arrondissement was completed in 1994 to a design of Dominique Perrault and contains four glass towers.
When was the Sainte Genevieve Library built? (If the question is unanswerable, say "unanswerable")
mid-1800s