To whet your appetite and keep your writing fingers limber, take a good look at the photo, or let a prompt settle in your mind. Set a timer for a reasonable amount of time, be that five, fifteen, or thirty minutes. Then start writing.
Your character wants to build a castle in an unconventional place, but doesn’t have the skills or money at present. How does she succeed against the odds?
If you could live anywhere in the world, where would it be and why?
Think of an existing castle and tell its story.