  We present total and linearly polarized 3 mm Global mm-VLBI Array images of a
sample of blazars and radio galaxies from the VLBA-BU-BLAZAR 7 mm monitoring
program designed to probe the innermost regions of active galactic nuclei (AGN)
jets and locate the sites of gamma-ray emission observed by the Fermi-LAT. The
lower opacity at 3 mm and improved angular resolution, on the order of 50
microarcseconds, allow us to distinguish features in the jet not visible in the
7 mm VLBA data. We also compare two different methods used for the calibration
of instrumental polarisation and we analyze the resulting images for some of
the sources in the sample.
