In the years 965/72 the German emperors donated the two farms Pfäffikon and Wollerau to the monastery of Einsiedeln. The Benedictine abbey built a storehouse in Pfäffikon to store the donations in kind from the population. In the middle of the 13th century Abbot Anselm von Schwanden had today's castle tower built to ward off enemy attacks and to protect the income from the monastery lands. In 1299 the complex was reinforced with great effort with walls, ramparts and moats.
Since the complex repeatedly had to serve as an abbot's residence, residential buildings were erected near the tower at the beginning of the 15th century under the direction of Abbot Burkhard von Weissenburg. From then on the castle was called the "Weissenburg". In 1567 Abbot Joachim von Eichhorn erected a Gothic chapel on the present site, which was rebuilt in Baroque style in 1785.
The castle complex served the monastery as an administrative centre until the 18th century and was eventually replaced by the newly built baroque governor's office next door. As a fortified building, Pfäffikon Castle was not only under the control of Einsiedeln Monastery, but also of the "Schirmvögten über die Höfe", the Lords of Rapperwil, the Count of Habsburg, Zurich and Schwyz. As a result, the castle was involved in numerous warlike conflicts.
The end of Weissenburg:
- 1798 Most of the castle complex was destroyed by Napoleon's troops.
- 1820 The remaining walls around the tower were demolished and the abbey and chapel were rebuilt.
- 1839 The rotten roof of the tower was replaced by the present roof truss.
- 1928 Renovation of the castle chapel.
- 1986-88 Chapel, tower and moat are renovated under the direction of Einsiedeln Abbey and the Pro Schloss Pfäffikon association.