**Description:**\\
Magnetic fields are ubiquitous in the Universe and affect almost all astrophysical processes, but our knowledge is still rather limited. I will present and discuss the various methods to observe interstellar magnetic fields. A tool to determine field strengths from radio synchrotron intensity, developed at MPIfR, will be demonstrated. A selection of fascinating results on galactic magnetic fields, mostly achieved by our pioneering group, will be presented.\\