  We present radio continuum polarimetry observations of the nearby edge-on
galaxy NGC 253 which possesses a very bright radio halo. Using the vertical
synchrotron emission profiles and the lifetimes of cosmic-ray electrons, we
determined the cosmic-ray bulk speed as (300+/-30) km/s, indicating the
presence of a galactic wind in this galaxy. The large-scale magnetic field was
decomposed into a toroidal axisymmetric component in the disk and a poloidal
component in the halo. The poloidal component shows a prominent X-shaped
magnetic field structure centered on the nucleus, similar to the magnetic field
observed in other edge-on galaxies. Faraday rotation measures indicate that the
poloidal field has an odd parity (antisymmetric). NGC 253 offers the
possibility to compare the magnetic field structure with models of galactic
dynamos and/or galactic wind flows.
