An older idea of small gate at the edge of a forest. The blerb at the bottom says that nobody ever returns from the forest, and that is where I got the story idea. The thumb-nail overview of the story was that at the center of the forest, there was a great castle. The castle, and the town around it, built then transported all the clouds in the sky. They had giant lightning guns to protect and defend themselves. They used floating ships with huge fans to move the clouds around.