The Kaiserliche Burg, or Imperial Castle, occupies one corner of the old town just off the Stadtplatz. Its claim to fame is the death of Emperor Maximilian I within these walls in 1519, after a journey that turned out to be his last. The building has been remodelled many times — most of what you see now is 16th and 17th century work — but the great hall still has the atmosphere of an imperial residence.
It now houses the Stadtmuseum Wels, which traces the city's history from Roman Ovilava through the medieval trading era and into the 20th century. The collection includes an interesting selection of Roman finds, plus rooms devoted to Maximilian himself. The castle courtyard hosts open-air concerts and a Christmas market in season.