An eye-catcher on Idstein’s König Adolf Platz is the town hall with its striking red façade. The building was erected in 1698 as a bridge over what was then the main road. Behind it, on a rocky outcrop, is Idstein’s old castle. In the 18th century, Idstein’s town hall housed only two offices as well as a guardroom, a detention cell, the town servant’s flat and the granary. In 1928 the building was partially destroyed by a rockfall and then by fire in 1947. The main damage was to the Estates Hall, the Mayor’s Room and part of the staircase. The Idstein citizens’ office is still located here today.