  The three generation superstring models in the free fermionic models have had
remarkable success in describing the real--world. The most explored models use
the NAHE set to obtain three generations and to separate the hidden and
observable sectors. It is of course well known that the full NAHE set is not
required in order to construct three generation free fermionic models. I argue
that all the semi--realistic free fermionic models that have been constructed
to date correspond to $Z_2\times Z_2$ orbifolds. Thus, the successes of the
semi--realistic free fermionic models, if taken seriously, suggest that the
true string vacuum is a $Z_2\times Z_2$ orbifold with nontrivial background
fields and quantized Wilson lines.
