Le Bas-Plessis was originally an ancient fiefdom and lordship under the jurisdiction of Montrevault. In the 15th century, it belonged to the Chenu family, who obtained it through the marriage between the knight Pierre Chenu and Jeanne Bérard, lady of Bas-Plessis, the daughter of Jean Bérard and Gervaise de Marigny.
Pierre Chenu, a knight of the Order of the King, obtained on December 23, 1602, the right to establish the land as a chatelain with the right of provostship, seal, measurement, baking oven, and mill. This right was granted to him by his suzerain, Charles Turpin, Count of Montrevault.
On November 2, 1666, François de Villoutreys and his wife, Renée Chenu, took possession of it.
During the Vendée War, the castle provided refuge to the wounded Lescure. In 1794, the feudal castle was set on fire during a battle, and only two towers remained, bordering the current pond. The castle was rebuilt in a neo-classical style in 1845 and expanded with a wing in 1875 to house the library of the Marquis de Villoutreys.
The remains of the medieval castle consist of two round towers with conical slate roofs. The first floor of the north tower serves as a chapel. A curtain wall connects these two towers. These are the parts that are listed as historical monuments.
Saint-Georges de Boscherville Abbey is a former Benedictine abbey. It was founded in about 1113 by Guillaume de Tancarville on the site of an earlier establishment of secular canons and settled by monks from the Abbey of Saint-Evroul. The abbey church made of Caumont stone was erected from 1113 to 1140. The Norman builders aimed to have very well-lit naves and they did this by means of tall, large windows, initially made possible by a wooden ceiling, which prevented uplift, although this was replaced by a Gothic vault in the 13th century. The chapter room was built after the abbey church and dates from the last quarter of the 12th century.
The arrival of the Maurist monks in 1659, after the disasters of the Wars of Religion, helped to get the abbey back on a firmer spiritual, architectural and economic footing. They erected a large monastic building one wing of which fitted tightly around the chapter house (which was otherwise left as it was).