'Imperial' in the Bible

The gates of the rivers [surrounding Nineveh] are openedAnd the palace [of sun-dried brick] is dissolved [by the torrents].

After reading the letter, he asked which province Paul was from, and when he learned that he was from Cilicia [an imperial province],

Now when it was determined that we (including Luke) would sail for Italy, they turned Paul and some other prisoners over to a centurion of the Augustan Regiment named Julius.

My imprisonment in [the cause of] Christ has become common knowledge throughout the whole praetorian (imperial) guard and to everyone else.