Saint-Pierre-de-Plesguen () is a former commune in the Ille-et-Vilaine department in Brittany in northwestern France. On 1 January 2019, it was merged into the new commune Mesnil-Roc'h. Personalities Hughes Felicité Robert de Lamennais lived in Saint-Pierre-de-Plesguen during the 19th century. Population Inhabitants of Saint-Pierre-de-Plesguen are called saint-pierrais in French. See also Communes of the Ille-et-Vilaine department References External links Official website Cultural Heritage Former communes of Ille-et-Vilaine