The Saturnian space environment is one of the most complex in our Solar System, because it interacts with all components of the Saturn system: the planet itself, its rings, numerous satellites and various dust, neutral and plasma populations. The interplay of plasmas of various origins and properties with the main three momentum sources of the Saturnian magnetospheric system, the solar wind, planetary rotation, and orbital motions, results in several different chemical and dynamic plasma regions. I will first start with a description of the key features of Saturn's magnetosphere deduced from its broad variety of emissions, that enable us to study the Saturnian magnetosphere as an astrophysical object: a magnetosphere with a significant modulation by planetary rotation, partly controlled by its interaction with the solar wind, with a strong natural corotation electric field accelerating dust particles outward, and embedded into a broad neutral cloud of hydrogen and water products. I shall then explore in-depth the Saturnian plasma and fields environment thanks to the combined operation of an outstanding instruments suite with the orbital tour of the Cassini/Huygens spacecraft. I shall describe some of the most interesting features of this emerging new view of Saturn's magnetosphere, which include a very interesting 'rings magnetosphere', a very dynamic 'water magnetosphere', a very rich variety of 'satellite-magnetospheric interactions', and a puzzling 'magnetosphere in rotation'. All these observations strongly emphasize the need for a really interdisciplinary investigation of this fascinating world.