"I think that's why I'm so keen to return," Albus said, his tone almost wistful. "I miss the castle. There was so much to do there and so little time. Besides, there are far more happy memories inside the castle walls then out of it. I like knowing that I end up back at Hogwarts - it's comforting even though I know it's not possible to happen again, unless the castle suddenly exists here in this time as well."