空城只有旧梦在只留旧梦守空城
[kōng chéng zhĭ yŏu jiù mèng zài zhĭ liú jiù mèng shŏu kōng chéng]
A metaphor where an abandoned place symbolizes memories lingering within, possibly referring to an old relationship or period filled with shared recollections that still persist amidst emptiness and solitude.