Eijsden Castle

Kasteel Eijsden is a castle just outside the eponymous Eijsden with a long history, which you can read more about here: nl.wikipedia.org/wiki/Kasteel_Eijsden
The castle is privately owned and cannot be visited. The gardens can be visited for free.

The castle in Maasland Renaissance style dates from 1636 and has hardly been changed since its construction. The eastern facade of the gate tower was collapsed into the moat in 1952, making renovation necessary. The castle is one of the top 100 Dutch UNESCO monuments. The park is open to visitors.
Source: walking guide - Flanders route GR 128

Tip: if you keep walking straight ahead from the main entrance you will reach the Maas. Look left and you will see a small path. Walk a few meters on it and see how the Voer flows into the Maas here. A beautiful view of a surprisingly peaceful spot on the beautiful grounds of the castle where you also walk a beautiful piece of wild garlic path.