空中楼阁

Explanation: Hanging in the air attic. False analogy from the real thing or a fantasy. 　　Usage: Partial official; as subject, object; containing derogatory 　　Source: Song of the question, "You Hokkeji" poem: "air knot F Hall, Yibiao the clouds." 　　Examples: Facts, things apply to Chen, is not false as, well-founded that also; virtual persons, ~, free form, invisible that also. (Qing Li Yu, "Xian Qing Ou Ji Structure First") 　　Riddle: Temple; moon; Moon Palace Thesaurus Group:  absurd and unreasonable, fictitious zilch, flyaway, a mare's nest, like a dream and a bubble's shadow, Mirage sea City, Ivory tower fantasy