空城已旧旧人已故
[kōng chéng yĭ jiù jiù rén yĭ gù]
This expresses a melancholic view on the passing of time and changes that occurred within it: The 'city'(could also mean any other meaningful places in a broad context) is left empty now because its previous inhabitants or familiar things/people have gone over the course of time; thus making them feel deserted and aged, emphasizing the impermanence of everything in life, including relationships and places