  In the framework of the Sine-Gordon (SG) theory we will present the
construction of a dynamical Virasoro symmetry which has nothing to do with the
space-time Virasoro symmetry of 2D CFT. Although, it is non-local in the SG
field theory, nevertheless it gives rise to a local action on specific
N-soliton solution variables. These {\it analytic} variables possess a
beautiful geometrical meaning and enter the Form Factor expressions. At the
end, we will also give some preliminary hints about the quantisation.
