Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Ruined City Free.
Ruined City v1.1
This package contains 55 prefabs (over 150 models), a complete scene, 13 ruined buildings, many debris parts and other decoration models. In this version we added new prefabs for climbing plants, and lot of decoration objects like lamps, barriers.
Thanks to good LOD system you can make really huge cities in unity format.
We added new optimised scene with PostProcessing effects like in video.
To get same look please attach provided PostProcessing profile to camera.
Added 20 new prefabs to make better scene. New video added with PostProcessing effects. Added new LOD stages for every model. Each prefab now have its own LODGroup with 3 LODs.