Tristan und Isolde (Tristan and Isolde), WWV 90, is a music drama in three acts by Richard Wagner set to a German libretto by the composer, loosely based on the medieval 12th-century romance Tristan and Iseult by Gottfried von Strassburg. First conceived in 1854, the music was composed between 1857 and 1859 and premiered at the Königliches Hoftheater und Nationaltheater in Munich on 10 June 1865 with Hans von Bülow conducting. While performed by opera companies, Wagner preferred the term Handlung (German for “plot” or “action”) for Tristan to distinguish its structure of continuous narrative flow (“endless melody”) as distinct from that of conventional opera at the time which was constructed of mundane recitatives punctuated by showpiece arias, which Wagner had come to regard with great disdain.