  We present an X-ray and radio study of the wind nebula surrounding the
central pulsar PSR J1811-1925 in the supernova remnant G11.2-0.3. Using high
resolution data obtained with the Chandra X-ray observatory and with the VLA
radio telescope we show the X-ray and radio emission is asymmetric around the
pulsar, despite the latter's central position in the very circular shell. The
new X-ray data allow us to separate the synchrotron emission of the pulsar wind
nebula from the surrounding thermal emission and that from the pulsar itself.
Based on X-ray data from two epochs, we observe temporal variation of the
location of X-ray hot spots near the pulsar, indicating relativistic motion. We
compare thermal emission observed within the shell, which may be associated
with the forward shock of the pulsar wind nebula, to thermal emission from a
nearby portion of the remnant shell, the temperature of which implies an
expansion velocity consistent with the identification of the remnant with the
historical event of 386 A.D. The measured X-ray and radio spectral indices of
the nebula synchrotron emission are found to be consistent with a single
synchrotron cooling break. The magnetic field implied by the break frequency is
anomalously large given the apparent size and age of the nebula if a spherical
morphology is assumed, but is consistent with a bipolar morphology.
