Die Walküre
Just finished watching Wagner's "The Valkyrie" on DVD, as performed at The Met in 1990. I thought it was magnificent. I mentioned in my post about Das Rheingold that it was clear Tolkien had mined the same mythology, and this point was made even more clear by this opera --- Turin Turambar and Nienor Niniel from The Silmarillion are reflections of the same legend giving rise to Siegmund and Siegislinde from the opera.