Senses
空中楼阁/ 空中樓閣 castle in the air
unrealistic plans, theories, or imaginary things that have no basis in reality
空中楼阁/ 空中樓閣 brilliant and farsighted
(literary) an metaphors for a person who is exceptionally brilliant, insightful, or high-minded
空中楼阁/ 空中樓閣 mirage
towers or pavilions seen in the sky; a mirage