  We point out that the moduli sector of the $(2,2)$ string compactification
with its nonperturbatively preserved non-compact symmetries is a fertile
framework to study global topological defects, thus providing a natural source
for the large scale structure formation. Based on the target space modular
invariance of the nonperturbative superpotential of the four-dimensional N=1
supersymmetric string vacua, topologically stable stringy domain walls are
found. They are supersymmetric solutions, thus saturating the Bogomolnyi bound.
It is also shown that there are moduli sectors that allow for the global
monopole-type and texture-type configurations whose radial stability is ensured
by higher derivative terms.
