Wallraf-Richartz-Museum & Fondation Corboud

This guide to the Wallraf-Richartz-Museum turns on a February 2008 discovery: restorers preparing a painting called On the Banks of the Seine by Port Villez, signed Claude Monet and hanging here since 1954, for x-ray and infrared study before an exhibition. The scans revealed a careful underdrawing and a fake aging glaze no real Monet should have, plus a signature drawn twice in two different inks. The painting had hung, unquestioned, among the museum's genuine Impressionist collection for fifty-four years.