All 3 Uses

although
in
Washington Square, by Henry James
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As an anatomist, it is really a pleasure to me to see such a beautiful structure; although, if people were all like him, I suppose there would be very little need for doctors.†
Chpt 7 *

although = even though -- used to connect contrasting ideas
We know, however, that Morris possessed the virtue of self-control, and he had, moreover, the constant habit of seeking to be agreeable; so that, although Mrs. Penniman's demeanour only exasperated his already unquiet nerves, he listened to her with a sombre deference in which she found much to admire.†
Chpt 15
The year that had elapsed since her brother's death reminded her—of that happy time, because, although Catherine, in growing older, had become a person to be reckoned with, yet her society was a very different thing, as Mrs. Penniman said, from that of a tank of cold water.†
Chpt 34

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)