  Was the Milky Way galaxy a low-luminosity active galactic nucleus (AGN) in
the past? Can we find traces of remnant structures supporting this idea? What
is the three-dimensional arrangement of matter around our central supermassive
black hole? A number of fundamental questions concerning our own Galactic
center remain controversial. To reveal the structure of the high-energy sky
around our galactic core, a technique more sensitive to the morphology of the
emitters than spectroscopy is needed. In this lecture note, I describe how
X-ray polarimetry can open a new observational window by precisely measuring
the three-dimensional position of the scattering material in the Galactic
center. The observed polarization degree and polarization position angle would
also determine unambiguously the primary source of emission and trace the
centennial history of our supermassive black hole by detecting echoes of its
past activity thanks to astrophysical mirrors. Finally, the synergy between
X-ray polarimetry and infrared and radio observations can be used to better
constrain the geometry in the first hundred parsecs around the Galactic center.
