basis of scenes from the life of Christ on the walls and ceiling; for example The Wedding at Cana on the south wall is largely based on Rubens's painting The Feast of Herod which hangs today in the National Gallery of Scotland in Edinburgh. The church's name refers to the church union declared in Idstein in 1817 whereby the Reformed and Lutheran churches in the Duchy of Nassau united to the Protestant Church in Nassau, today the Protestant Church in Hesse and Nassau. Residence palace The Renaissance-style Schloss was built in 1614–1634 by Jost and Henrich Heer (Höer) for Count Ludwig (d. 1627) and his son Count Johann (d. 1677) by incorporating older building materials. It stands on a craggy massif between the town's two brooks. It is believed that the crags on which the palace is built were already built up in the 11th century. A bridged gap in the crags separates it from the old castle area from the 11th century; through this gap today runs an important road. During the time when the last Idstein prince, Georg August Samuel von Nassau-Idstein (1665–1721), was ruling, the building was given its interior design under Maximilian von Welsch's guidance. The now partly missing ceiling stucco was done by Carlo Maria Pozzi. At the main entrance door is a great alliance coat of arms of Count Johann and his consort from about 1635. The palace has been home to the Pestalozzischule since 1946 and may be visited on guided tours. Castle and Hexenturm The castle in the area stretching from the gateway arch building on the town side to the bridge over to the Schloss arose between 1497 and 1588. With the remodelling done on the palace itself in the 17th century, this area also underwent far-reaching changes, partly losing its defensive functions, which, it is worth noting, were no longer up to date anyway. The castle's keep, known as the Hexenturm, tall, walls more than thick, even given overall diameter of just under , is Idstein's oldest building. Dendrochronological borings show that work began on the tower as early as 1170 (not, as had long been assumed, about 1350). It received its "butter churn" shape, built in stages, about 1500. (Building researchers see in it a rare time capsule, because in the 20th century, almost nothing was changed beyond the last work in 1963, which entailed nothing more than some