I can't I'm afraid. All I remember is the floating city that no-one believed in anymore except this one little boy. And then a girl fell out of the sky, and it turns out she lived in the floating city. And they go on a big quest to find it!
It was a great film, but I never got to see it all the way through.
EDIT: Wahey! I found it! Laputa: Castle in the Sky! You have no idea how happy I am now.![]()