  Starting from a sigma-model for a doubled target-space geometry, we show that
the number of target-space dimensions can be reduced by half through a gauging
procedure. We apply this formalism to a class of backgrounds relevant for
double field theory, and illustrate how choosing different gaugings leads to
string-theory configurations T-dual to each other. We furthermore discuss that
given a conformal doubled theory, the reduced theories are conformal as well.
  As an example we consider the three-dimensional SU(2) WZW model and show that
the only possible reduced backgrounds are the cigar and trumpet CFTs in two
dimensions, which are indeed T-dual to each other.
