Rapperswil Castle was built in the early 13th century AD by the House of Rapperswil. It is surrounded on three sides by the Lake Zürich and by those upper section on the northwestern Seedamm area. Thus, the castle was well protected, dominating the old town of Rapperswil, and controlling the water way between Walensee and Lake Zürich on its most narrow part, as well as the medieval Gotthard Pass route between Lombardy and Zürich.
Rapperswil Castle dates back around 1200 to 1220, and it was first mentioned in 1229 on occasion of the foundation of the Rüti Abbey. The castle was 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. As before in the 11th and 12th century AD, the family acted as Vogt of the Einsiedeln Abbey. Sandstone from the Lützelauisland was used to build the castle, the town walls and the city.
The first chapel was associated to the castle, but the chapel was located outside of its walls and separated by a trench. The preceding building of the Liebfrauenkapelle was built as an ossuary around 1220 to 1253.
In 1350 an attempted coup by the aristocratic opposition (a central person was Count Johann II) in the city of Zürich was forcefully put down, and the town walls of Rapperswil and the castle were destroyed by Rudolf Brun. Eis-zwei-Geissebei, a Carnival festival hold in Rapperswil on Shrove Tuesday, may go back to the siege and destruction of the city of Rapperswil. The battlements and the castle were rebuilt by Albrecht II, Duke of Austria in 1352/54.
After the extinction of the line of Habsburg-Laufenburg in 1442, the castle was given to the citizens of Rapperswil. Ending Old Zürich War, Rapperswil was controlled by the Swiss Confederation from 1458 to 1798 as a so-called Gemeine Herrschaft, i.e. under control of two cantons of the Old Swiss Conferation and their representant, a Vogt, and Rapperswil castle became an administration site respectively military base and prison.
Over the course of time, the castle fell into disrepair. In 1870 the castle was leased for 99 years from the local authorities by a post-November 1830 Uprising Polish émigré, Count Wladyslaw Broel-Plater, who had been in Switzerland since 1844. At his own expense he restored the castle, and on 23 October 1870 the Polish National Museum was established.
References:The Chapel of St. Martin is the only completely preserved Romanesque building in Vyšehrad and one of the oldest in Prague. In was built around 1100 in the eastern part of the fortified outer ward. Between 1100 and 1300, the Rotrunda was surrounded by a cemetery. The building survived the Hussite Wars and was used as the municipal prison of the Town of the Vyšehrad Hill.
During the Thirty Years’ War, it was used as gunpowder storage, from 1700 to 1750, it was renovated and reconsecrated. In 1784, the chapel was closed passed to the military management which kept using it as a warehouseand a cannon-amunition manufacturing facility. In 1841, it was meant to be demolished to give way to the construction of a new road through Vyšehrad. Eventually, only the original western entrance was walled up and replaced with a new one in the sountren side. The dilapidating Rotunda subsequently served as a shelter for the poor.