has a total area of 98.9 square miles (256.7 km²). The town is found in the middle of Waldviertel at the confluence of the Kamp and Zwettl rivers.
After Vienna and Wolfsberg in Carinthia, it is the third largest municipality in Austria by area. The name originates from Slavic “svetla” meaning “glade”. Although the etymology suggests an early population of Slavic people no archeological evidence has been found yet. Zwettl was founded by the knights of Kuenring and was first mentioned in a monastery record in 1139. It was granted town privileges on December 28, 1200. Today, the Cistercian convent in Zwettl houses the only remaining manuscript of the life of Saint Agnes Blannbekin.