Although... / Even though... / Even if...
Versatile concessive connector. Aunque + indicative = even though (known fact). Aunque + subjunctive = even if (hypothetical). Very widely used.
Although he was tired, he kept working.
I'll do it even if I don't like it.
Even though it seems difficult, it's possible to achieve.
Although it's raining, I'll go.
Even if it's late, I'll call.