  Classical gravitating field theories reduced to three dimensions admit
manifest gauge invariances and hidden symmetries, which together make up the
invariance group G of the theory. If this group is large enough, the target
space is a symmetric space G/H. New solutions may be generated by the action of
invariance transformations on a seed solution. Another application is the
construction of multicenter solutions from null geodesics of the target space.
After a general introduction on this sigma-model approach, I will discuss the
case of five-dimensional gravity, with invariace group SL(3,R), and minimal
five-dimensional supergravity, with invariance group G_{2(2)}. I will also
describe recent attempts at the generation of new charged rotating black rings.
