Stadtschloss, Parliament building in Mitte, Wiesbaden, Germany.

The Stadtschloss is a three-storey neoclassical palace with 145 rooms across several wings, built 1837–1841 by Georg Moller for the Dukes of Nassau. Its cream-coloured facade has rows of rectangular windows and a rounded central section with dark columns and steps; above the entrance runs the lettering "HESSISCHER LANDTAG". A slate roof laid in herringbone patterns tops the complex.

The palace was built in 1841 as a residence for the Dukes of Nassau and later served as a summer home for German emperors. In modern times, it was converted into the seat of the Hessian State Parliament, where regional governance continues today.

The name Schloßplatz comes from the palace itself. On 4 March 1848, some 30,000 citizens gathered in front of the building to press the Nine Demands of Nassau; Duke Adolph walked unguarded from the railway station through the crowd and announced his assent from the balcony. The square in front remains the address of the Hessian Landtag.

The building is the working seat of the Hessian State Parliament, so the interior is not open to tourists; visits are limited to organised tours arranged in advance. From the Schlossplatz you can see the cream-coloured facade with the lettering "HESSISCHER LANDTAG" above the columns of the rounded entrance. The square itself is freely accessible and gives the best view of the ensemble.

The building combines three originally separate structures—the green Kavaliershaus, the red Wilhelmsbau, and the main palace—into a single unified facade. This skillful integration creates an enlarged plaza that unifies the view of the entire ensemble from the square.