  We present BVI photometry of the globular cluster NGC 6642 using the SOI
imager at the SOAR Telescope. The Colour Magnitude Diagrams (CMD) reach
$\approx$1.5mag in V below the main sequence turn-off. A comparison of the
overall sequences, and in particular the Red Giant Branch slope of NGC 6642
with that of M~5 indicates that the two clusters must have a similar
metallicity of [Fe/H]$\approx$-1.3. We also obtain for NGC 6642 a reddening
E(B-V)=0.42$\pm$0.03, and a distance from the Sun of d$_{\odot}$=7.2$\pm$0.5
kpc. Therefore NGC 6642 is a moderately metal-poor globular cluster, spatially
located in the bulge, at a galactocentric distance of R$_{\rm GC}$$\approx$1.7
kpc. The comparison of CMDs of NGC 6642 with those of M~5 shows that there is a
very good match of magnitude difference between turn-off and horizontal branch,
suggesting comparable ages. M~5 has an age typical of the halo globulars, and
consequently NGC 6642 is coeval with the halo. NGC 6642 is a good candidate to
be one of the few genuine metal-poor and old {\it bulge} clusters, and might be
one of the most ancient fossils in the Galaxy.
