  Spitzer Space Telescope imaging as part of the Galactic Legacy Mid-Plane
Survey Extraordinaire (GLIMPSE) reveals a previously unidentified low-latitude
rich star cluster near l=31.3 degrees, b=-0.1 degrees. Near-infrared JHK'
photometry from the Wyoming Infrared Observatory indicates an extinction of A_V
~ 15+/-3 mag for cluster members. Analysis of 13CO features along the same
sightline suggests a probable kinematic distance of 3.1 -- 5.2 kpc. The new
cluster has an angular diameter of ~1-2 pc, a total magnitude m_{K_0}=2.1
corrected for extinction, and a luminosity of M_K ~ -10.3 at 3.1 kpc. In
contrast to young massive Galactic clusters with ages <100 Myr, the new cluster
has no significant radio emission. Comparison to theoretical K-band luminosity
functions indicates an age of at least several Gyr and a mass of at least 10^5
solar masses. Unlike known old open clusters, this new cluster lies in the
inner Galaxy at R_{GC} ~ 6.1 kpc. We designate this object ``GLIMPSE-C01'' and
classify it as a Milky Way globular cluster passing through the Galactic disk.
We also identify a region of star formation and fan-shaped outflows from young
stellar objects in the same field as the cluster. The cluster's passage through
the Galactic molecular layer may have triggered this star formation activity.
