  HST observations have shown that low-redshift 3CR radio galaxies often
exhibit a point-like optical component positionally coincident with the
GHz-frequency radio core. In this paper we discuss the correlation between the
luminosities of the radio, optical and X-ray cores in these objects, and argue
that all three components have a common origin at the base of the relativistic
jets. In unified models, FRI radio galaxies should appear as dimmed, redshifted
versions of BL Lac objects. We show that such models are consistent with the
spectral energy distributions of the radio galaxies only if the nuclear X-ray
emission in radio galaxies is inverse-Compton in origin.
