Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Street & Subway Backgrounds HD Free.
Street & Subway Backgrounds HD v1.0
Street & Subway Backgrounds HD is a collection of 3 seamless level backgrounds and props. You can use it as level constructor. Street & Subway Backgrounds HD is compatible with our Character Editor assets.
List of backgrounds:
● Street
● Station
● Train
Specs:
● HD resolution 1920×1080
● Seamless
● Level props (boxes, barrels, tires, graffity and other)
● PSD source included
● PNG examples