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:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.