Columbia subject headings:
Harvard subject headings:
Claudius, Emperor of Rome, 10 B.C.-54 A.D.
Harbors--Rome.
Ostia (Extinct city)--Antiquities, Roman.
Rome--Navy
Ships, Wooden--Rome--History.
Princeton subject headings:
Harbors--Italy--Rome.
Rome (Italy)--Antiquities.
Shipbuilding--Italy--Rome.
Ships, Wooden.