Constructs are anywhere from 5-7 floors with at least 1 outside section. Floors can be SC as long as they are not unfun difficulty spikes or they ramp the general difficulty of the Construct up into SC territory.
Fun Fact: CoPA was originally going to be the hardest citadel ever made that WASN'T a joke, which is why the victory message placeholder exists. However, now that it has been turned into a Construct for Area 1, it has no use.