This Special Building has got an idle animation in the Flash version. In this case, it is the glowing of the radioactive symbol to green and back to black.
In the Flash version, there is a spelling mistake in the quote. Instead of "Ground Zero", the description of this Special Building calls the upgrade "Ground-Zero", with hyphen.
This also applies to the steam/mobile version. It is unknown if this is intended or not.
Although it looks like it takes up only 3 tiles in a "L" shape, it actually takes up a full 2 by 2 area of four tiles. The bottom right tile cannot have anything placed on it.