Because I love that castle. It's beautiful.
I started working on art for this comic over a year ago, and at the time the beginning of the story was much later chronologically and set in a castle. The style for the art was different at the time as well, which is why the header is more painterly than what I'm actually using in the comic.
Eventually when I draw a castle in the comic, I might still use Neuschwanstein as reference.
I'm glad you like my comic!