Every race has upgrades for units or special structures which can only be built on such sites.

I might add that just following orders to make a special structure is not a criminal offense.

"The regular bridge, yes, but not the special temporary structure that your friends the Norvels had ready for you."

But that's not enough to bring someone into a special structure.

The virus must recognize special structures on the surface of the cell.

But he insists that neither would have made any difference were it not for the special structure of our hands.

The relationship between the two is so intimate that it has led to the evolution of special structures and behaviors in both organisms.

There was also a third category of larger "special structures" for strategic purposes.

These are special structures, the like of which is not found anywhere else in Europe.

Rice decided to change the special structure that had been built to coordinate counterterrorism policy.