  Recently, string theory on Calabi--Yau manifolds was constructed and was
shown to be a fully consistent, space--time supersymmetric string theory. The
physically interesting case is the case of three generations. Intriguingly, it
appears at the present that there is a unique manifold which gives rise to
three generations. We describe in this paper a full fledged string theory on
this manifold in which the complete spectrum and all the Yukawa couplings can
be computed exactly.
