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.
Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.