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:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.