Nüremberg is a city in the state of Bavaria, Germany. It is also in the administrative region of Middle Franconia and is situated on the Pegnitz River and the Danube Canal.The population is approximately 500,132 people. Nüremberg was an early center of humanism, science, printing, and mechanical invention and contributed much to the science of astronomy. For instance, the work of Nicolaus Copernicus was published in 1543. Printers and publishers have a long history in Nüremberg. Many of these publishers worked with well-known artists of the day to produce books that could also be considered works of art. Wagner made his most famous member, Hans Sachs, the hero of his opera Die Meistersinger von Nüremberg. Nuremberg boasts artistry and architecture unparalleled elsewhere. There are at least 10 churches located within Nüremberg, including the ruins of an ancient house of worship. Of course, another integral site to be toured is Nüremberg Castle. The Johannisfriedhof contains many old graves; the Rochusfriedhof, or the Wöhrder Kirchhof are near the old town.