...does castles in our dreams exist?

Can anyone tell me if 'castles' we build in our dreams have at least existed in our dreams? If there is Déjà vu then I may think that it is psychologically possible that it may exist...

If that is so, can I have a dream tonight? Then, at least there is some hope in it then in real life cause it will not happen at all.

However, my problem is; I only get to sleep so late, and when I finally sleep, I don't dream. So... looks like the sandcastles at East Coast Park or Sentosa is easier than making one in my dreams!