Autumn series of free baroque music concerts in Marseilles include eight concerts at Marseille's Saint Michel church with Haydn, Bach and Mozart - traditionally in October-November. Timetable check at http://www.marseille.fr/siteculture.
Since 2002 the Tout l'monde dehors or 'Everybody Outside' festival has been bringing open air arts and music to Lyon, completely free of charge, throughout the summer from mid June to September. Check program here.
Ancient Roman theater - Arenes de Lutece - built in the 1st century AD and being one of two important remains from Gallo-Roman period in Paris is hidden in the middle of apartment buildings of 5th arrondissement. Not so easy to find, so even more exciting to see.
Musee Cernuschi exhibits high level Asian art and it is the 2nd most important Asian art museum in France, and 5th most important in Europe. Free admission to permanent collection.
Maison de Balzac displays showcase the novelist’s keepsakes, paintings and engravings, objects belonging to his friends, family and contemporaries, and a sizeable collection of original works, manuscripts and illustrations. In this house Honore Balzac wrote "La Comédie Humaine". Free admission to permanent collection.
Maison de Victor Hugo - Victor Hugo lived here from 1832 to 1848 and wrote some of his major works here: Marie Tudor, Ruy Blas, Les Burgraves, Les Chants du crépuscule, Les Voix intérieures, a large part of Les Misérables. Free admission.
Modern Art Musuem of City of Paris - collection begun in 1937 when the building was created and then significantly enhanced through the generosity of private collectors. Free admission to the permanent collections.
Musee Carnavalet - With around 600,000 exhibits spread over more than one hundred rooms, the musée Carnavalet houses the largest overall number of collections in the city of Paris. Free admission to permanent collections and themed exhibitions.