  Using the Mopra telescope, we have undertaken a 3-mm spectral-line imaging
survey of a 5 x 5 arcmin^2 area around Sgr B2. We covered almost the complete
spectral the range from 81.7 to 113.5 GHz, with 2.2 MHz wide spectral channels
or ~ 6 km/s, and have observed 24 lines, with 0.033 MHz wide, or ~ 0.1 km/s
channels. We discuss the distribution of around 50 lines, and present
velocity-integrated emission images for 38 of the lines. In addition, we have
detected around 120 more lines, mostly concentrated at the particularly
spectral line-rich Sgr B2(N) source. There are significant differences in
molecular emission, pointing to both abundance and excitation differences
throughout the region. Seven distinct spatial locations are identified for the
emitting species, including peaks near the prominent star forming cores of Sgr
B2(N), (M) and (S) that are seen in IR-to-radio continuum images. The other
features are a 'North Ridge' and a 'North Cloud' to the north of the Sgr B2
N-M-S cores, a 'South-East Peak' and a 'West Ridge'. The column density, as
evident through C^{18}O, peaks at the Sgr B2(N) and (M) cores, where strong
absorption is also evident in otherwise generally bright lines such as HCO^{+},
HCN and HNC. Most molecules trace a ridge line to the west of the Sgr B2 N-M-S
cores, wrapping around the cores and extending NE to the North Cloud. This is
most clearly evident in the species HC_{3}N, CH_{3}CN, CH_{3}OH and OCS. They
are found to be closer in distribution to the cooler dust traced by the sub-mm
continuum than either the warmer dust seen in the mid-IR or to the radio
continuum. The molecule CN, in contrast, is reasonably uniform over the entire
region mapped, aside from strong absorption at the positions of the Sgr B2(N)
and (M) cores.
