I'm going to be ambitious and try to recreate this ad:

Now, there are two main challenges: the building and the background pattern. 

The building is a matter of time and patience; technique-wise, it's rather straightforward. It would be good to learn how to take advantage of its symmetry - I'm sure there's a mirror tool or something.

The grid, however, requires more ingenuity. Perhaps there's some trick to this, like using the Blend tool...