The Stadtschloss (City Palace) was built in 1840 as a simple city palace in Late Classical style for Wilhelm, Duke of Nassau. It was a popular family abode for the Prussian royal and the German emperor's families.

 

Since 1946, it has been the seat of the Hessian Landtag (State Parliament). Regular guided tours: 1st Saturday of the month at 10 a.m.