The oldest part of the present Bossenstein Castle is the square keep, probably built before the 14th century by a Joannes van Busco or Van den Bossche. Not much later it went to the Van Berchem family. They are supposed to have made some major alterations to the castle. They sold it in 1544 to Guilelmus van der Rijt, who was a member of the city council of nearby Antwerp. In the deed of sale the castle was described as an impressive estate, with a lot of outbuildings. Of these outbuildings nothing survives.
In 1655 it was sold again, this time to Willem van Halmale. He rebuilt the castle into a beautiful residence, which was still fortified. During the 18th century the castle changed hands several times between several noble families. Between 1798 and 1843 the castle was used by religious institutions. In 1906 the castle underwent restoration works, saving it from slow decay.
At present the castle is surrounded by the grounds of an 18-hole golf and polo club. The terrain of this club is probably not freely accessible. There is however a long distance walking path leading through the golf course which is. As far as I know the castle itself can not be visited.
References:The Pilgrimage Church of Wies (Wieskirche) is an oval rococo church, designed in the late 1740s by Dominikus Zimmermann. It is located in the foothills of the Alps in the municipality of Steingaden.
The sanctuary of Wies is a pilgrimage church extraordinarily well-preserved in the beautiful setting of an Alpine valley, and is a perfect masterpiece of Rococo art and creative genius, as well as an exceptional testimony to a civilization that has disappeared.
The hamlet of Wies, in 1738, is said to have been the setting of a miracle in which tears were seen on a simple wooden figure of Christ mounted on a column that was no longer venerated by the Premonstratensian monks of the Abbey. A wooden chapel constructed in the fields housed the miraculous statue for some time. However, pilgrims from Germany, Austria, Bohemia, and even Italy became so numerous that the Abbot of the Premonstratensians of Steingaden decided to construct a splendid sanctuary.