The Mus ? ? e Marmottan ( 2 Rue Louis-Boilly ) is devoted mainly to Impres ? ­ ? ­ sion ? ­ ist paintings , with key works by Monet , Pissarro , Gauguin , and Sisley .
Monet , Pissarro , Gauguin , and Sisley were the most important Impressionists .