  We present a way of constructing string solutions around non-trivial
gravitational backgrounds. The proposed solutions are constructed using $N = 4$
superconformal building blocks with $\hat c = 4$. We give two different and
inequivalent realizations of non-trivial four-dimensional subspaces, and we
show the emergence of the $N = 4$ globally defined superconformal symmetry. The
existence of $N = 4$ world-sheet symmetry stabilizes our solutions and implies
in target space a number of covariantized supersymmetries around space-time
dependent gravitational and dilaton backgrounds.
