The first settlement arose on today's site of the city as early as 2,500 BC. The mighty castle was constructed by the Dukes of Zähringen. It has a fortification tower built between 1180 and 1190. The halls of the tower house a historical museum that exhibits artifacts from prehistory and early history as well as medieval objects, weapons and uniforms from the 18th and 19th century, a ceramic collection and a toy exhibition. The castle's most splendid exhibit is the restored Knights Hall, dating to the 12th century.
Further sights in the Old Town include the town church with its tower dating back to about 1330, the town hall from the 16th century, the Old Town itself and the numerous restaurants and cafés along the Aare River.
- Old town with castle - shopping and culture combined at close proximity.
- Wocher Panorama - the 7.5-metre high and 38-metre long 360° circular painting in the Schadau Park depicts the town of Thun at about 1810.
- Stockhorn, Niesen, Niederhorn - accessible by mountain transport facilities, they are fantastic vantage points in the immediate vicinity.
- Cruising on Lake Thun - motor- and paddle-powered ships sail to Interlaken regularly (in winter motor ships only).
- Water sports by and in Lake Thun - the clean water of the lake is perfect for bathing, sailing, surfing, diving etc.