The Castle of the Pomeranian Dukes stands on a hill above the Oder River, a Gothic and Renaissance complex that served as the seat of the Pomeranian dukes from the 14th century until the Duchy's incorporation into Brandenburg-Prussia in 1637. It's the dominant monument of the old city and the logical starting point for any visit.
The castle is partly a reconstruction — significant portions were destroyed in World War II bombing — but it has been carefully restored and now houses several museums, a concert hall in the crypt, and a viewpoint tower. The exhibits cover the Pomeranian dukes' history, regional art, and the city's complicated 20th-century story. The tower gives excellent views over the Oder and the rebuilt city below. Allow two hours if you want to cover the exhibitions thoroughly.