Untertaunuskreis (district seat, Bad Schwalbach), which in the course of district reform was merged with the Rheingau-Kreis into the new Rheingau-Taunus-Kreis. With about 25,700 inhabitants, Idstein is the second biggest town in the district (after Taunusstein). History Idstein, which had its first documentary mention in 1102 as Etichenstein, was granted town and market rights in 1287 by King Rudolph of Habsburg. Besides the Hexenturm near the old Nassau castle that has already been mentioned, the town has a mediaeval town centre with many timber-frame buildings. The town's oldest preserved house was originally built in 1410. From the documentary mention in 1102 until 1721, Idstein was, with interruptions, residence of the Counts of Nassau-Idstein and other Nassau lines. One of the Counts, Adolf of Germany, was, as a compromise candidate, the Holy Roman Emperor from 1292 to 1298, later falling in battle against the anti-king Albrecht I of Habsburg. The Nassau Counts' holdings were subdivided many times among heirs, with the parts being brought together again whenever a line died out. This yielded an older Nassau-Idstein line from 1480 to 1509, later merging once again with Nassau-Wiesbaden and Nassau-Weilburg and, from 1629 to 1721, a newer Nassau-Idstein line. In the 17th century, Count Johann of Nassau-Idstein persecuted witches in Idstein. In 1721, Idstein passed to Nassau-Ottweiler, and in 1728 to Nassau-Usingen, thereby losing its status as a residence town, although it became the seat of the Nassau Archives and of an Oberamt. Nassau-Usingen was united with Nassau-Weilburg in 1806 into the Duchy of Nassau, becoming a member of the Confederation of the Rhine. After the Austro-Prussian War in 1866, Prussia annexed the Duchy as the Prussian province of Hesse-Nassau. The residential palace from the 17th century is used by the Pestalozzischule as a school building. It was expanded with a new building below the palace. From the late 18th century to the mid 20th, Idstein was the centre of an important leather industry. During the Second World War, many women became forced labour for work in the tanneries. In 1959, the dominant tannery in the middle of the town core was shut down for economic reasons. The lands right at the edge of the Old Town lay empty and were used until the 1980s as a carpark. Today, new shops and apartments surround the Löherplatz, which is now a marketplace. The private Kalmenhof clinic in Idstein was drawn into the Nazi