Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Office Buildings Set Free.
Office Buildings Set v1.0
This is a set of 6 buildings sharing the same textures. It comes with day and night textures.
Materials: day, night, glass
Textures: day diffuse and night diffuse, both with cut out textures in alpha and normal bump with specular in alpha. PSD textures are also included.