  The effective action of string theory in three dimensions is investigated,
incorporating the Lorentz and gauge Chern-Simons terms in the definition of the
Kalb-Ramond axion field strength. Since in three dimensions any three-form is
trivial, the action can be reformulated by properly integrating the axion out.
The circumstances under which it can be recast in form of topologically massive
gravity coupled to a topologically massive gauge theory are pointed out.
Finally, the strong coupling limit of the resulting action is inspected, with
the focus on the roles played by the axion and dilaton fields.
