  By a toroidal compactification with a vortex like configuration of tachyon
fields, the unoriented bosonic string in 26 dimensions becomes equivalent to 10
dimensional string theory with gauge group $SO(32)\times G$ where $G$ has rank
16. The reduction from SO(8192) to SO(32) is induced by the action of
non-abelian Wilson lines which twists the tachyon. The additional enhanced
gauge symmetry $G$ appears from closed string sector by Frenkel-Kac
construction. We also examine the consistency of the tachyon condensation.
