Line elements showing the orientation of the projected magnetic field (90deg to the synchrotron polarization angle) from the Planck 28.4 GHz data at 2° resolution. The region within b = ± 10deg has been masked out (grey rings) to avoid crowding of the vectors. The colour scale shows the polarized intensity. The maps are in orthographic projection, centred on the Galactic poles, north (left) and south (right). Light dashed circles show the outlines of Loops I to IV, as defined by Berkhuijsen et al. (1971) and shown in Fig. 20; the red dashed line is the locus of filament IIIs from Vidal et al. (2015).