Traces of past activity in the Galactic Centre
  The Milky Way centre hosts a supermassive Black Hole (BH) with a mass of
~4*10^6 M_Sun. Sgr A*, its electromagnetic counterpart, currently appears as an
extremely weak source with a luminosity L~10^-9 L_Edd. The lowest known
Eddington ratio BH. However, it was not always so; traces of "glorious" active
periods can be found in the surrounding medium. We review here our current view
of the X-ray emission from the Galactic Center (GC) and its environment, and
the expected signatures (e.g. X-ray reflection) of a past flare. We discuss the
history of Sgr A*'s past activity and its impact on the surrounding medium. The
structure of the Central Molecular Zone (CMZ) has not changed significantly
since the last active phase of Sgr A*. This relic torus provides us with the
opportunity to image the structure of an AGN torus in exquisite detail.
