strange new buildings all over

It seems like my city, and so many others, are now surrounded by giant gray and white featureless, usually windowless, buildings. Not that many seem occupied now. Many have signs out front that say “available” or “hiring soon.”

My first suspicion is that it is some kind of corporate giveaway. Don’t just let them go tax free, build their building, too. I don’t know that, but you know.

What could it be?