So what's the coolest or most mind blowing thing you have ever seen or done in a lucid dream?

I have not had a lot of lucid dreams yet, but the coolest thing I have seen was when I came across a huge city inhabited by clay men (and some normal people). I can't really do it justice by explaining it, but weird and cool things happened around every corner. There was some person with me that I knew in the dream. He explained to me something profound about the city's existance, but I can't remember the exact quote anymore. Despite my bad summary, it was pretty cool.