Millen Castle, locally known as Kasteel Millen, lies near the village of Nieuwstadt, in the province of Limburg in the Netherlands.
The present remains of Millen Castle date back to the 14th century. This castle was probably preceded by a wooden tower house, encircled by a palisade, which was destroyed around 1287. We know that there was a castle on a motte in Millen in 1326.
Around 1365 the building of the now remaining ruin was started by Jan van Meurs on orders of Eduard, Duke of Gelre. Around the oval plateau a ring wall was built which incorporated two towers. One round keep, with 2,6 meters thick walls, next to the gate and a horseshoe shaped tower with a well. The ring wall had ramparts standing on large arches. The inner courtyard probably ran up to the middle were maybe a building stood.
In 1389 the castle was incorporated in the Fortress Line of Brabant which probably led to some alterations. It is assumed that during that period the oldest, kidney shaped bailey was build which was provided with a gatetower, a drawbridge and ramparts on its northern side. The bailey was connected to the main castle with a wooden bridge.
Around 1450 a second, oval ring wall was built on about 5 meters distance of the first one. This ring wall, with ramparts, incorporated 7 outward projecting, square towers. The gatetower, with pointed arches, of the former second bailey probably dates back to that period. This bailey was connected to the main castle with a stone bridge.
In 1499 Millen Castle was annexed by the Duchy of Gulik and consequently lost its military function. And although there were plans for demolition in 1538, the castle was again strengthened in 1566. In 1650 however the role of Millen Castle finally ended when duke Wolfgang Wilhelm von Pfalz-Neuberg gave permission for its demolition. He however stipulated that the round keep and a wall part incorporating a postern were left standing as remainders of a great past.
Around 1700 the present bailey was build with the use of building materials from the ruin. In 1803 the castle was put up for a public auction by the French occupiers who had confiscated it. In 1816 Millen Castle became Dutch as result of a border adjustment while the village of the same name stayed German. The border is now only some 25 meters apart from the bailey.
The bailey is now lived in by 5 families.