I had this dream long time ago, but it was so unique, I memorized it. In the dream, it was a day as usual, and then I saw something that looked like an alien spacecraft. It was huge and was moving across the sky, very slowly. The shape was gigantic, rectangular and flat (when seen from the side) . It looked a little bit like a huge blimp, but it was flat. It also looked completely outlandish, some kind of a wonder of technology, being so huge and flying so low and so slowly.
Then something happened- the spacecraft hit a building, or a tree, and it started to fall apart! This wonder of technology broke into many pieces, one by one- and there was no explosions; it just started to loose parts one by one and finally fell on the ground. I did not see any aliens coming out of it. Overall, it looked like a ridiculously complex technology falling apart as a result of a minor accident.
The dream was very visually vivid.