  We report the discovery of a very unusual, highly asymmetric radio galaxy
whose radio jet, the largest yet detected, emits strongly polarized synchrotron
radiation and can be traced all the way from the galactic nucleus to the hot
spot located ~440 kpc away. This jet emanates from an extremely massive black
hole (>10^9 solar mass) and forms a strikingly compact radio lobe. No radio
lobe is detected on the side of the counterjet, even though it is similar to
the main jet in brightness up to a scale of tens of kiloparsecs. Thus, contrary
to the nearly universal trend, the brightness asymmetry in this radio galaxy
increases with distance from the nucleus. With several unusual properties,
including a predominantly toroidal magnetic field, this Fanaroff-Riley type II
megajet is an exceptionally useful laboratory for testing the role of magnetic
field in jet stabilization and radio lobe formation.
