Idstein Castle was built in the 11th century, presumably by order of Henry IV, as a hilltop castle and was the residence of the Counts of Nassau for a long time. The northern part of the complex, the so-called upper castle, was rebuilt into a Renaissance castle from 1614 to 1634, which is why Burg Idstein is often referred to as Schloss Idstein. The former administrative building of the counts in the southern part of the castle complex was replaced in the 16th century by half-timbered buildings with ornamental gables. The most famous part of Idstein Castle is certainly the Hexenturm, a keep dating back to 1170, which dominates the Idstein townscape and is considered the landmark of the town in the Taunus.
