Act III. The scene is a sepulchral vault, enclosing the tomb of

Charlemagne in the Cathedral of Aix-la-Chapelle. The tomb is entered by a heavy door of bronze, upon which is carved in large characters the word "Charlemagne." Steps lead to the great door of the vault. Other and smaller tombs are seen and other doors that give on other passageways. Two lamps, suspended from the roof, shed a faint light.

It is into this sombre but grandiose place the _King_ has come in order to overhear, from within the tomb of his greatest ancestor, the plotting of the conspirators. His soliloquy, "Oh, de' verd'anni miei" (Oh, for my youthful years once more), derives impressiveness both from the solemnity of the situation and the music's flowing measure.

[Music: Oh de' verd'anni miei]

The principal detail in the meeting of the conspirators is their chorus, "Si ridesti il Leon di Castiglia" (Let the lion awake in Castilia). Dramatically effective, too, in the midst of the plotting, is the sudden booming of distant cannon. It startles the conspirators. Cannon boom again. The bronze door of the tomb swings open.

Then the _King_ presents himself at the entrance of the tomb. Three times he strikes the door of bronze with the hilt of his dagger. The principal entrance to the vault opens. To the sound of trumpets six Electors enter, dressed in cloth of gold. They are followed by pages carrying, upon velvet cushions, the sceptre, crown, and other imperial insignia. Courtiers surround the Emperor. _Elvira_ approaches. The banners of the Empire are displayed. Many torches borne by soldiers illuminate the scene. The act closes with the pardon granted by the _King_, and the stirring finale, "Oh, sommo Carlo!" (Charlemagne!)