German, as well as Czech, has two words for a castle. One is “das Schloss” which means a luxurious aristocratic residence. The other one is “die Burg” and means a fortified luxurious aristocratic residence.
From what I have been able to decipher on German Wikipedia the castle in Idstein used to be both of those. Originally it started with a lookout tower (the previously mentioned Hexenturm) around which a fortified residence was built. Sometime around the Renaissance period the castle was rebuilt from fortress into purely representative luxurious dwelling.
First picture shows the castle as seen from the town. The castle itself is located uphill and can only be accessed via the gate near Rathaus.
At the foot of the Hexenturm is this beautiful building connecting the base of the tower with the gatehouse (named “Alte Kanzlei”). This building, at least its lower parts, is what remains of the original fortress. There were some significant damages to be seen, right behind the gatehouse the original stone wall was bulging out and it had markers on it probably to keep an eye on the bulge. Unfortunately in our somewhat chaotic and unguided stroll through the town I did not make more pictures of the remnants of the original fortifications, because I did not know where to look and for what.
However I did make a picture of the main castle building. With “chemtrails” behind it. Today it serves as a high school, a much better purpose than a demonstration of wealth and power.