  A class of 2-dimensional models including 2-d dilaton gravity, spherically
symmetric reduction of d-dimensional Einstein gravity and other related
theories are classically analyzed. The general analytic solutions in the
absence of matter fields other than a U(1) gauge field are obtained under a new
gauge choice and recast in the conventional conformal gauge. These solutions
imply that Birkhoff's theorem, originally applied to spherically symmetric 4-d
Einstein gravity, can be applied to all models we consider. Some issues related
to the coupling of massless scalar fields and the quantization are briefly
discussed.
