In the late 1800s Lohengrin was the most popular opera in the world— “the crown,” Tchaikovsky called it, “of Wagner’s creations.” It was also the first of Wagner’s operas to be performed at the Liceu. This season, the composer’s great-granddaughter, Katharina Wagner—director of the Bayreuth Festival—makes her own debut at the Liceu, directing a new production of Lohengrin that stars tenor Klaus Florian Vogt and soprano Evelyn Herlitzius. —L.J.