  The magnetic fields in our Milky Way can be revealed by the distribution of
Faraday rotation measures (RMs) of radio sources behind the Galaxy and of radio
pulsars inside the Galaxy. Based on the antisymmetry of the Faraday sky in the
inner Galaxy to the Galactic coordinates, the magnetic field toroids above and
below the Galactic plane with reversed field directions exist in the Galactic
halo and have been included in almost all models for the global magnetic
structure in the Milky Way. However, the quantitative parameters, such as the
field strength, the scale height, and the scale radius of the toroids are hard
to determine from observational data. It has long been argued that the RM
antisymmetry could be dominated by the local contributions of the interstellar
medium. Here we discount the local RM contributions measured by pulsars mostly
located within 5 kpc and get the first quantitative estimate of the size of
magnetic toroids in the Galactic halo. They are huge, starting from a
Galactocentric radius of less than 2 kpc to at least 15 kpc without field
direction reversals. Such magnetic toroids in the Galactic halo should
naturally constrain the physical processes in galaxies.
