  We present high resolution HST imaging of the nebula associated with the
galactic LBV candidate HD 168625, together with ISO imaging and AAT echelle
spectroscopy. The overall nebular morphology is elliptical with the major axis
at PA ~ 120 deg. The dimensions of the nebula are 12'' x 16''.7 at Halpha and
15''.5 x 23''.5 at 4 micron. In the HST Halpha image, the nebula is resolved
into a complex structure of filaments and arcs of different brightness. The
asymmetry is lost in the HST continuum image where the nebula appears more
diffuse and richer in filaments and clumps with the shape of cometary tails. At
11.3 micron the nebular emission peaks in two diametrically opposite lobes,
placed on the nebula boundaries and along its major axis. A very faint loop is
also visible at optical wavelengths, north and south of the shell. We suggest
that the nebula is an ellipsoid with projected sizes of 14'' and 9'' (0.19 pc x
0.12 pc) along the RA and DEC directions, respectively. This ellipsoid is
expanding at 19 km/s and is dynamically as old as ~ 4800 yrs; it probably
interacts with the stellar wind and the loop so that PAH emission is detected
from its caps, i.e. the lobes seen in the ISO images. The chemistry of the loop
suggests that it is composed of un-processed material, probably from the local
interstellar medium swept by the stellar wind.
