  A large class of new 4-D superstring vacua with non-trivial/singular
geometries, spacetime supersymmetry and other background fields (axion,
dilaton) are found. Killing symmetries are generic and are associated with
non-trivial dilaton and antisymmetric tensor fields. Duality symmetries
preserving N=2 superconformal invariance are employed to generate a large class
of explicit metrics for non-compact 4-D Calabi-Yau manifolds with Killing
symmetries.
