  We show that a post-Riemannian spacetime can accommodate an internal symmetry
structure of the Yang-Mills prototype in such a way that the internal symmetry
becomes an integral part of the spacetime itself. The construction encrusts the
internal degrees of freedom in spacetime in a manner that merges the gauging of
these degrees of freedom with the frame geometrical gauges of spacetime. In
particular, we prove that the three spacetime structural identities, which now
become ``contaminated'' by internal degrees of freedom, remain invariant with
respect to internal gauge transformations. In a Weyl Cartan spacetime, the
theory regains the original form of Einstein's equations, in which gauge field
sources on the r.h.s. determine on the l.h.s the geometry of spacetime and the
fields it induces. In the more general case we identify new contributions of
weak magnitude in the interaction between the Yang-Mills field and gravity. The
merger of spacetime with internal degrees of freedom which we propose here is
not constrained by the usual Coleman-Mandula considerations.
