  We present multiwavelength observations of this S-type symbiotic LMXB which
consists of a 2-min X-ray pulsar accreting from an M6 III giant. This is the
only symbiotic system definitely known to contain a neutron star. The steady
interstellar extinction toward the binary (Av=5) contrasts the variable N_H
inferred from X-ray measurements, most likely evidence for a stellar wind. The
mass donor is probably near the tip of the first-ascent red giant branch, in
which case the system is 3-6 kpc distant and has an X-ray luminosity of 10^37
erg/s. It is also possible, though less likely, that the donor star is just
beginning its ascent of the asymptotic giant branch, in which case the system
is 12-15 kpc distant and has an X-ray luminosity of 10^38 erg/s. However, our
measured Av argues against such a large distance. We show that the dense (10^9
cm^-3) emission-line nebula enshrouding the binary is powered by UV radiation
from an accretion disk. The emission-line spectrum constrains the temperature
and inner radius of the disk (and thus the pulsar's magnetic field strength),
and we discuss this in the context of the accretion torque reversals observed
in the pulsar. We also show that the binary period must be >100 d and is most
likely >260 d, making GX 1+4 the only known LMXB with Porb>10 d. If the mass
donor fills its Roche lobe, the mass transfer must be highly super-Eddington,
requiring much mass loss from the binary. We discuss the alternative that the
disk forms from the slow, dense stellar wind expected from the red giant.
