Der Ring des Nibelungen

Richard Wagner, a German composer, began writing the librettos first, then the music, to Der Ring des Nibelungen in 1848, and completed the four operas, collectively known as The Ring cycle; Das Rheingold (The Rhine Gold), Die Walkure (The Valkyrie), Siegfried, and Gotterdammerung (The Twilight of the Gods), in 1874. It was an exaltation of early Norse mythology and German heroic poetry, which facinated Wagner. They were first performed in sequence at the Festspielhaus in Bayreuth, Bavaria, Germany on August 13th, 14th, 16th, and 17th, 1876.  The original Festspielhaus, which became the home of the Ring cycle, was built to Wagner’s specifications at the command of Bavaria’s King Louis II.
 
Der Ring des Nibelungen, conducted by the late Sir George Solti in Vienna between 1958 and 1965, with the Wiener Philharmoniker under the Decca label, was voted twice as the greatest recording of all time. The luminary cast included Birgit Nilsson, Hans Hotter and Kristen Flagstad. This is a new high definition 24 bit/192 kHz transfer of the original master tapes for Dolby Atmos by Decca’s pioneer producer John Culshaw. 

Reference: (2019, October 17), A Beginner's Guide to Wagner's RING Cycle. Lyric Opera of Chicago. https://www.lyricopera.org/lyric-lately/beginners-guide-wagner-ring-cycle/