All 5 Uses

although
in
The Phantom of the Opera
(Auto-generated)

Yes, he existed in flesh and blood, although he assumed the complete appearance of a real phantom; that is to say, of a spectral shade.†
Chpt Prol. *

although = even though -- used to connect contrasting ideas
And I should be ungrateful indeed if I omitted, while standing on the threshold of this dreadful and veracious story, to thank the present management the Opera, which has so kindly assisted me in all my inquiries, and M. Messager in particular, together with M. Gabion, the acting-manager, and that most amiable of men, the architect intrusted with the preservation of the building, who did not hesitate to lend me the works of Charles Garnier, although he was almost sure that I would never return them to him.†
Chpt Prol.
R. "No, monsieur, no, although, when walking behind her, I took no pains to deaden the sound of my footsteps.†
Chpt 5
This side does not lead to the lake nor to the house on the lake ...But perhaps he knows that we are at his heels ...although I promised him to leave him alone and never to meddle in his business again!†
Chpt 20
Although Erik announced to me very solemnly that he had changed and that he had become the most virtuous of men SINCE HE WAS LOVED FOR HIMSELF—a sentence that, at first, perplexed me most terribly—I could not help shuddering when I thought of the monster.†
Chpt 21

Definitions:

(1) (although)
even though -- used to introduce an idea that contrasts with or makes the main statement surprising

At the start of a sentence, although can play a role similar to words like however, yet, still, even so, on the other hand, or nonetheless—all of which signal contrast. In the middle of a sentence, although can sometimes be used where but or though might also work, but though or but often sound more natural. For example, "She's a great teacher, though not the most popular" is usually smoother than "She's a great teacher, although not the most popular."
(2) (meaning too rare to warrant focus)