A castle that vanishes at the first gust of wind is worthless. A skyscraper within your mind will never fall down.
Altough it looks strong, basically the castle is a static building, walled and fenced, resistent to outsider, and usually only used for survival in war. When attacked, there must be a limit to it. An when the peace comes, it is difficult to grow because of its resistance concept. The evolution in our civilization shows that the concept of castle is not a valid for defense or attack.
So, how about our thoughts?