How does one build a provincial barracks?

[nasher168]

I've just started a Roman campaign and defeated Hannibal. Unfortunately, this has cost me a good half of my army and I obviously need to replenish my numbers. However, in all my settlements I find that I am incapable of building a barracks to any higher level, and the Building Browser yields no information on how I might go about building one.
So my question is this: what are the requirements for building a provincial barracks?

[Ejergard]

You need to build the next level of government building and then the provincial barracks to be able to recruit principe/triarii.
It will take a few turns to get there, in the meantime you can use hastati to fill up the gaps.

[nasher168]

Ah okay. I've begun building a Governor's Palace, so I'll be able to build a provincial barracks after that, then?

[Ejergard]

That should be it

[nasher168]

Okay. Thanks.