The city of the sky actually tells us that although our ideals were finally shattered, we had a pursuit, a brave heart and a beautiful process, so we had no regrets. If you want to know more about it, you can go to see this animated film. Just like its theme song, it expresses such a spirit with a touch of sadness, full of longing, yearning, forge ahead, persistence, knowing the result of tragedy, never looking back and marching forward.