  Classical black holes shield us from the singularities that inevitably appear
in general relativity. Being singularity regularization one of the main
landmarks for a successful theory of quantum gravity, quantum black holes are
not obliged to hide their inner core from the outside world. Notwithstanding
the aforesaid, it is often implicitly assumed that quantum gravity effects must
remain confined to black hole interiors. In this essay we argue in the opposite
direction, discussing theoretical evidence for the existence of strong
correlations between the physics inside and outside non-singular black holes.
We conclude that astronomical tests of the surroundings of black holes can
provide invaluable information about their so-far unexplored interiors.
