Füssen's old town castle, perched on a hill above the Altstadt and reached by a stiff ten-minute walk up. The building was the late-Gothic summer residence of the prince-bishops of Augsburg from the 15th century and is now a museum of Bavarian state painting from the 14th to the 18th centuries.
The single most striking feature is the painted Knights' Hall, with a wooden coffered ceiling from 1499, and especially the trompe-l'oeil exterior of the inner courtyard — the architectural decoration (windows, columns, statues) is painted on the flat walls in a deceptively three-dimensional way. The exterior trick is most effective in late-afternoon sun, when you can stand in the courtyard and try to spot the joins. The view from the castle terrace looks down over Füssen Altstadt and across to the Alps.