Thank you to all who answered! The correct answer is although. The two words mean almost the same thing (both express contrast) but they belong to different grammatical categories, and that's what decides which one fits. Although is a conjunction. It connects two clauses (subject + verb). ✅ Although it was raining, we went for a walk. Despite is a preposition. It must be followed by a noun or an -ing form, never a full clause. ✅ Despite the rain, we went for a walk. ✅ Despite it being rainy, we went for a walk.