Think Federal police. It's big.
On the floor estimation, I'm not too sure. It'll house the reception ( which will cover about 4 storeys ), Offices ( 6 connected storeys), Senior offices ( 4 separated storeys ) , Cells ( 3 / 4 storeys under the roof ) , Roof ( 2 storeys + Actual roof ) , and then the Armories, Judicial areas, Holding areas, Meeting rooms , etc. So all In all, it's at least 28 storeys. Eventing this will be a pain in the arse.