In the courtyard of the Jardin du Palais Royal is Daniel Buren’s installation of black-and-white striped columns (officially known as “Les Deux Plateaux”). They have caused a lot of controversy since they were installed in 1986. Apparently the mayor of Paris even tried to stop this installation.
This is an overview. There are about 260 of these columns in varying heights meant to contrast with the historic columns of the arcade.