You might think you know the impressionists inside out, given that theirs is one of the most popularised artistic movements of all time. But you'd be wrong, as this exhibition proves. From Switzerland to Mexico via Italy and Britain, a few rare pieces have been hiding away in private collections, emerging just for an exhibition at the Musée Marmottan-Monet. The show celebrates the museum's 80th birthday with 100 masterpieces, most of which have never been seen by the public. Caillebotte, Monet, Pissarro, Renoir, Degas, Corot, Boudin are all on the menu – a tantalising proposition.