Rüti Abbey
Rapperswil Castle dates back around 1200 to 1220 AD, and it was first mentioned in 1229 on occasion of the foundation of the Rüti Abbey. The castle and the fortifications of the former locus "Endingen" (given by the Einsiedeln Abbey) were built by Count "Rudolf II" and his son "Rudolf III von Rapperswil", when the nobility of Rapperswil moved from Altendorf ("Alt-Rapperswil") across the lake to the other side of the so-called "Seedamm", maybe to establish their own parish church and to avoid to go the mess, by crossing the lake, in St. Martin Busskirch. As before in the 11th and 12th century AD, the family acted as "Vogt" of the Einsiedeln Abbey. Sandstone from the Lützelau island was used to build the castle, the town walls and the city.