Unit > Building with Radius on build

[CaptainYak]

So when I started my map I wasn't aware how everything worked, and I made all of my "towers" as immobile units.

This works great, except it still lets these units be built on non buildable area. It also doesn't show the radius around the unit (it's range) when I build it.

Any ideas on how to make these affects apply to my units?

Thanks