  We report the preparation of the interface between graphene and the strong
Rashba-split BiAg$_2$ surface alloy and investigatigation of its structure as
well as the electronic properties by means of scanning tunneling
microscopy/spectroscopy and density functional theory calculations. Upon
evaluation of the quasiparticle interference patterns the unpertrubated linear
dispersion for the $\pi$ band of $n$-doped graphene is observed. Our results
also reveal the intact nature of the giant Rashba-split surface states of the
BiAg$_2$ alloy, which demonstrate only a moderate downward energy shift upon
the presence of graphene. This effect is explained in the framework of density
functional theory by an inward relaxation of the Bi atoms at the interface and
subsequent delocalisation of the wave function of the surface states. Our
findings demonstrate a realistic pathway to prepare a graphene protected giant
Rashba-split BiAg$_2$ for possible spintronic applications.
