In 1954, directed for the first time by the grand master Luchino Visconti, Maria Callas brought La Scala to its knees as the reluctant Roman priestess Julia. Gaspare Spontini’s stately drama remains a rarity, however, and few have followed in La Divina’s footsteps, but never fear. The intrepid Elza van der Heever, who shaved her head for her blazing Metropolitan Opera portrayal of Elizabeth I, loves a challenge. —M.G.