Rue des Petits-Champs marks the boundary between the arrondissements I and II--the odd numbers in arrondissement I, the even ones in arrondissement II. The street was opened in 1634. Many of its old houses still stand and show us, without and within, some interesting architectural features of past days. The hôtel Tubeuf, No. 8, destined with adjoining mansions to become the Bibliothèque Nationale, was, tradition tells us, staked at the gambling table and won by the statesman Mazarin. The Cardinal bought two adjoining _hôtels_ and surrounding land as far as the Rue Colbert and built thereon his own fine mansion, using the two _hôtels_ as wings. The first books placed there were those of his own library, a fine collection, taken at his death, according to the directions of his will, to the Collège des Quatre Nations, known to-day as the Institut Mazarin. The Cardinal’s vast mansion was divided among his heirs and in its different parts was put to various uses during following years till, in 1721, it was bought by the Crown. The King’s library was then taken there from Rue Vivienne, where it had been placed in 1666, and soon afterwards opened to the public. The greater part of the building has been reconstructed in modern times and enlarged. The blackened walls of a part of Mazarin’s mansion, that formed l’hôtel de Nivers, still stand at the corner of Rue Colbert. The chief entrance to the Library is in Rue de Richelieu. Engravings, medals, works of art of many descriptions connected with letters may be seen at what has been successively Bibliothèque Royale, Bibliothèque Impériale and is now Bibliothèque Nationale. The ceiling of the Galerie Mazarin is covered with splendid frescoes by Romanelli. The heart of Voltaire is said to be encased in the statue we see there. Madame de Récamier died at the Library in 1849; she had taken refuge there in the rooms of her niece, whose husband was one of the officials when the cholera broke out in l’Abbaye-aux-Bois. Opposite the Library, on the Rue Richelieu side, is the Square Louvois dating from 1839, on the site of two old _hôtels_ once there. There, in 1793, Citoyenne Montansier set up a theatre, known successively as Théâtre des Arts, Théâtre de la Loi and the Opéra.