Ruins of the Prinsenkasteel

At a stone’s throw of the Guldendal, in the middle of the Prinsenbos pond, the vestiges of the Prinsenkasteel loom high above the trees. A water castle surrounded by a park and other properties, this once mighty bastion used to be the home of the lords of Grimbergen after their fortress at the Borcht burned down during the Wars of Grimbergen (12th century). The castle has undergone many refurbishings over the course of the centuries.In 1944, retreating German soldiers set fire to the castle, after which it declined further into a ruin. Only the castle keep, i.e. the fortified residential area, remained intact and is currently being restored. Once the restoration works are completed, this tower will be repurposed as a part of the museum.


Here you'll find some 3D computer drawings created by students of the UCL Brussels. 

In close vicinity of the Guldendal, the remains of the Prinsenkasteel (Prince’s castle) loom high above the moat. A water castle with surrounding park and adjoining structures, this once mighty bastion was the residence of the lords of Grimbergen, ever since their stronghold on the motte in Borgt was burned to the ground during the war of Grimbergen (12th century). In the course of the centuries, the castle has undergone several renovations. In 1944, retreating German soldiers set fire to the castle, leaving it to decay further into a ruin. 

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The Prinsenkasteel, what a history!

The earliest texts mentioning a castle date from the fifteenth century. Since no archeological research has been carried out so far, we do not know if anything has been built on the premises of the Prinsenkasteel before that time. Historical sources speak of the stronghold being besieged by Maximilian of Austria in 1488 and destroyed completely by Albert of Saxony in 1489 – at least, that is how the phrase ‘fut rasé par terre’ has been interpreted. On the occasion of Open Monuments Day 2016, a specialist in medieval towers and castles visited the Prinsenkasteel. On the basis of the techniques used by the stonemason and the traces these techniques have left on the building stones, this researcher was able to date some of the buildings, or parts of them. It turned out that large parts of the donjon and maybe the second corner tower of the Prinsenkasteel were clearly built in the period 1400-1420. This means the castle was not ‘razed to the ground’ at the end of the fifteenth century. After the fifteenth century the castle was restructured and enlarged several times. Two stone pillars, standing at the entrance bridge to the island, are inscribed with the year 1610. In this year, the castle was refurbished into a country retreat, a ‘hof van plaisantie’ or ‘court of pleasure’. From the 17th century until after the Second World War, the castle was in the possession of several noble families. During the war, German soldiers took up residence in the castle, and set fire to it upon their departure. Since then, the castle has been a ruin that has partly been restored and consolidated.

The donjon

The donjon A donjon or keep is a medieval residential tower. From the twelfth century onwards, building and inhabiting residential towers became a true and proper fashion. The lords commissioning these towers wanted to have a safe retreat, in times that were far from safe. A donjon is therefore built to resist considerable sieges. But apart from this protective function, they were also certainly a means of expressing social status. People able to construct themselves such an edifice enjoyed high esteem in the Middle Ages.

The donjon of the Prinsenkasteel is a gate donjon, giving access to the stronghold. Donjon and stronghold could be closed off by means of a portcullis and two gates. Towers that combine the functions of access gate and residence are rare in Flanders.Every storey of a donjon has one or more specific functions. The first storey is usually used as a reception hall, but the less than luxurious furnishings of the first storey of the Prinsenkasteel suggest that here the space was put to different use. 

The second storey is without doubt the most important one. There is a large hearth, recesses with benches at the windows, and a toilet with a door that does not directly lead into the sitting room, a real luxury by medieval standards! From this storey you could also enter the wall-walk, making it the junction point from which the castle was controlled. 

The third storey was possibly the sleeping area. The recesses in the walls are of more recent date, holes cut out in order to let pigeons nest in them. Both this tower and the other corner tower were adapted to be used as pigeon towers in this manner.

The future of the Prinsenkasteel 

The MOT has big plans to turn the ruin of the Prinsenkasteel into a late medieval construction site. Our goal is to organise an aray of educational activities around the history of construction and building techniques. In order to do so, we have to wait for the restoration of the castle to be completed to safeguard it from further decay. 

In the mean time, the MOT, with the support of the province of Flemish Brabant, will set up a new exhibition in the donjon on stone building techniques of the late Middle Ages.


het MOT, Afdeling Guldendal- Guldendal 20, 1850 Grimbergen
Tel. +32 2 270 81 11 -