The Wasserkirche ('Water Church') of Zürich was first mentioned around 1250. It seems likely that the original building was used for cult meetings. The meetings were centred on a stone now located in the crypt of the church. According to medieval tradition, the site was used for the execution of Saints Felix and Regula. The church was built in the 10th century and modified at various points, culminating in a complete reconstruction that was completed in 1486.
During the course of the Reformation, the Wasserkirche was identified as a place of idolatry. Eventually it was secularised, becoming the first public library of Zürich in 1634, when it became a seat of learning that greatly contributed to the foundation of University of Zürich in the 19th century. The island was connected with the right bank of the Limmat in 1839 with the construction of the Limmatquai. The library was merged into the Zentralbibliothek in 1917, and the church was used as a storage room for crops for some time, until reconstruction work and archaeological excavations were undertaken in 1940. Following this the building was again used for services by the Evangelical-Reformed State Church of the Canton of Zürich.
The Helmhaus is an extension of the church to the north, first mentioned in 1253 as a court of criminal justice, at which time it was a simple wooden structure covering the eastern end of the bridge. It was extended to a larger wooden structure in 1563, and replaced with a stonework hall in 1791.
References:Ogrodzieniec Castle is a ruined medieval castle originally built in the 14th–15th century by the W³odkowie Sulimczycy family. Established in the early 12th century, during the reign of Boles³aw III Wrymouth, the first stronghold was razed by the Tatars in 1241. In the mid-14th century a new gothic castle was built here to accommodate the Sulimczycy family. Surrounded by three high rocks, the castle was well integrated into the area. The defensive walls were built to close the circuit formed by the rocks, and a narrow opening between two of the rocks served as an entrance.
In 1470 the castle and lands were bought by the wealthy Cracovian townsmen, Ibram and Piotr Salomon. Then, Ogrodzieniec became the property of Jan Feliks Rzeszowski, the rector of Przemy¶l and the canon of Cracow. The owners of the castle about that time were also Jan and Andrzej Rzeszowskis, and later Pilecki and Che³miñski families. In 1523 the castle was bought by Jan Boner.