The Imperial Castle — popularly called Zamek, simply "the castle" — is the most architecturally distinctive building in Poznan: a red-brick Neo-Romanesque palace built for Kaiser Wilhelm II at a time when Poznan was the Prussian city of Posen, capital of the German province of Posen. The architecture is monumental and somewhat pompous, which was rather the point. Today it houses a cultural centre with exhibition spaces, a cinema, a theatre, and several restaurants.
The interior is worth seeing for the throne room and the former royal apartments, which retain their Wilhelmine decoration. The castle also has a basement bar and music venue that is popular with Poznan's students, giving the Hohenzollern imperial architecture an entertainingly incongruous afterlife. The building sits in its own grounds at the western end of the city centre, a ten-minute walk from the Old Market Square.