This yearly event all over Europe encourages the public to discover museums that don't share the same limelight as that of the more popular museums. Lectures, performances and animations add flavor to the late-night event.
Because of the event, I was able to discover that in Paris, there are many museums that offer free entry to their permanent collections:
Musee d'Art Moderne de la Ville de Paris
Musee Cernuschi, Musee des Arts de L'Asie de la Ville de Paris
Musee de la Vie Romantique
Maison de Balzac
Petit Palais, Musee des Beaux-Arts de la Ville de Paris
May 16, 2009