Street level bill boards? Terrain idea

We got a box in the mail with some interesting packing material.

My wife gave me some and asked if I could use these for some kind of terrain piece.

Hmm?  What could these be?

15mm and 28mm models for scale.

My first thought (and only one so far) is to use them as billboards.  I plan to print out some signs and attach then to these.  

I think they would look good in an urban environment.

What do you think?

Any other ideas?