When we walked into our house for the very first time, I took one look at the beam connecting the loft above the kitchen to the wall and said something like "Oh, that's so going to be a problem with Necco". Necco has a deep love for heights and doing things that are really dangerous. This has lead to bright ideas like escaping outside and crawling underneath the neighbor's house.
Last week though, Necco finally crossed some invisible line into crazy cat territory when she figured out how to climb through the loft railing to get out onto the beam. See?
She's about 10-12 feet above any solid surfaces in this picture, just hanging out on her beam. She just sits out there, or strolls along the beam, or stands on the beam with her front paws on the wall. She clearly realizes that it bothers the two of us, because she's got a very satisfied air about her while she's out there. I'm not that worried that she'll actually get hurt if she falls from the beam, it's just that it's really disconcerting to be sitting in the living room and then looking up to see a cat hovering above you.