  We present Australia Telescope Compact Array (ATCA) observations of the
supernova remnant (SNR) G296.8-00.3. A 1.3-GHz continuum image shows the
remnant to have a complex multi-shelled appearance, with an unusual rectangular
strip running through its centre. HI absorption yields a kinematic distance to
the remnant of 9.6+/-0.6 kpc, from which we estimate an age in the range (2-10)
x 10^3 yr. The ATCA's continuum mode allows a measurement of the Faraday
rotation across the band, from which we derive a mean rotation measure towards
the SNR of 430 rad m^(-2). We consider possible explanations for the morphology
of G296.8-00.3, and conclude that it either has a biannular structure, as might
be produced through interaction with an asymmetric progenitor wind, or that its
appearance is caused by the effects of the surrounding interstellar medium.
  We argue that the adjacent pulsar J1157-6224 is at a similar distance as the
SNR, but that a physical association is highly unlikely. The pulsar is the only
detectable source in the field in circular polarization, suggesting a method
for finding pulsars during aperture synthesis.
