Wagner - Das Rheingold
Richard Wagner completed the first opera in the Ring Cycle in 1854 - after he had written the final three.
It's often said Wagner composed his Ring Cycle backwards, and it's not untrue - although Das Rheingold is the first in the sequence of his four epic dramas (ahead of Die Walküre, Siegfried and Götterdämmerung), it was conceived at the end of the composition process as a 'great prelude' to a gargantuan trilogy.
Considerably shorter than its three successors, the curtain rises showing three Rhine maidens at the bottom of the river, as a dwarf from Nibelung attempts to woo them. The three maidens, Woglinde, Wellgunde, and Flosshilde, share the story of a magical ring which grants the bearer the power to rule the world. The drama follows the dwarf, Alberich, who steals the ring and lays a curse on it when it is taken from him - resulting in fantastically operatic deaths and betrayals throughout the Cycle.
Das Rheingold was first performed at Munich on 22 September 1869, but the opera wasn't performed as Wagner intended it - as part of a typically Wagnerian large-scale production of all four operas in the cycle over four nights - until 13 August 1876.