  We present the discovery of non-thermal radio and X-ray emission positionally
coincident with the TeV $\gamma$-ray source HESS J1813--178. We demonstrate
that the non-thermal radio emission is due to a young shell-type supernova
remnant (SNR) G12.8--0.0, and constrain its distance to be greater than 4 kpc.
The X-ray emission is primarily non-thermal and is consistent with either an
SNR shell or unidentified pulsar/pulsar wind nebula origin; pulsed emission is
not detected in archival ASCA data. A simple synchrotron+inverse Compton model
for the broadband emission assuming that all of the emission arises from the
SNR shell implies maximum energies of $(30-450)(B/10 microG)^{-0.5}$ TeV.
Further observations are needed to confirm that the broadband emission has a
common origin and better constrain the X-ray spectrum.
