Levels: 1-3
Requires:

Levels 1-2: CC19

Level 3+: CC20

Function: Build Contractors that create various effects for your base. Come with 4 FREE Contractors!

Construction Yard

Levels: 1-5
Requires: 

Levels 1-2: CC19

Level 3+: CC20

Function: Build structures that you can place in your base to use as cover for buildings and units.

The Agency and Construction Yard will only allow you to place a set number of each type. If it shows the Place button greyed out, it means you already have one of that type in your base. You will need to scrap it and place the one that you want to use.
Similarly, you will not be able to start a resource build when you have items waiting to be placed. You can use gold but you still will need to make sure it is the only one of that type to be placed in the base.

Can I scrap or remove the Agency/Construction Yard buildings?
No; Once placed, these buildings will stay in your base. They keep their level through game updates and cannot revert or downgrade. 

Can I scrap or remove the Agents or Constructs from these buildings?
Yes; Once placed, click on a construct or agent to see the options to Scrap Building, Move, or enter Base Editor. Note: that scrapping an agent/construct will not return any resources or gold. Even if done right away.  
   

Why can't I start a build with resources?
You likely already have the maximum number of agents or construct of that type in your base. You can use gold to build it immediately, but you are still limited to the number you can put in the base itself. 

Why can't I place an agent/construct?
If it shows the Place button greyed out, it means you already have the max number of that type in your base. You will need to scrap once or more and place the one that you want to use.