I place these around the edge of the gaming table where the missing walls don't show up and look odd in photo's, but using them makes the game run a bit more easily and smoothly.
This is one of my favourite builds as it takes up almost a whole 12" square. I use it as two shops and four apartments.
I plan to add some signage and things once I've built a few more buildings to give mnore detail and depth.
Smaller builds below
Got a little alleyway that can be added if needed