Typical of the Middle Ages was its feudal system. Achel, Hamont and Lille, however, constituted a monastic domain for a long time, which depended on the episcopal city Maastricht. In 1309 Willem II Van Boxtel became the first lay lord of the monastic domain Grevenbroek. From 1338 onward Grevenbroek became a free manor. In 1401 Grevenbroek lost its independence to the prince-bishopric of Liege. At that time Willem Van Boxtel had already built a round defence tower (some contend it to have been a windmill, though it had a moat and other defence systems).
In the fifth room, which is the so-called castle-room, the middle ages are handled. You see some larger maquettes of two of the castles in our village: the defense tower (a keep), called "De Tomp" and the castle of Grevenbroek. A large quantity of medieval earthenware has been found during the excavations near these castles and is exhibited (beer-mugs, saucers, china). Further you can also seen some canon-balls that were used during the sieges at the two castles.