  We argue that classical spacetimes represent amplified information in the
holographic theory of quantum gravity. In general, classicalization of a
quantum system involves amplification of information at the cost of
exponentially reducing the number of observables. In quantum gravity, the
geometry of spacetime must be the analogously amplified information. Bulk local
semiclassical operators probe this information without disturbing it; these
correspond to logical operators acting on code subspaces of the holographic
theory. From this viewpoint, we study how bulk local operators may be realized
in a holographic theory of general spacetimes, which includes AdS/CFT as a
special case, and deduce its consequences. In the first half of the paper, we
ask what description of the bulk physics is provided by a holographic state
dual to a semiclassical spacetime. In particular, we analyze what portion of
the bulk can be reconstructed as spacetime in the holographic theory. The
analysis indicates that when a spacetime contains a quasi-static black hole
inside a holographic screen, the theory provides a description of physics as
viewed from the exterior (though the interior information is not absent). In
the second half, we study how and when a semiclassical description emerges in
the holographic theory. We find that states representing semiclassical
spacetimes are non-generic in the holographic Hilbert space. If there are a
maximal number of independent microstates, semiclassical operators must be
given state-dependently; we elucidate this point using the stabilizer formalism
and tensor network models. We also discuss possible implications of the present
picture for the black hole interior.
