Wiesbaden City Palace ( or Wiesbadener Stadtschloss) is a neo-classical building in the center of Wiesbaden, Germany. It was completed in 1841 as the principal city residence of the Dukes of Nassau. The palace has several wings, 145 rooms, and is architecturally integrated with a group of ancillary buildings constructed both before and after it was built. With ornate towers, gables and a slate roof laid in herringbone patterns, the three-story complex lends charm and its name to the central square of Wiesbaden: Palace Square .