Texturing a single mesh

I made a height map so that it looks like a city scape, from a single plane mesh.
Now I would like to add a texture to each individual ‘building’ (raised area of the mesh).

Is that possible,to add a different texture to areas of the same mesh,or is that a tricky operation?

You’ll need to UV map the area if your going to a single texture. Here is an example that might suit you
http://www.biorust.com/index.php?page=tutorial_detail&tutid=85