The quest for identifying the sources of Galactic Cosmic Rays is a century old, ongoing effort.
I will summarize recent results and illustrate the challenges currently faced by the standard paradigm associating galactic Cosmic Ray origin to Supernova Remnants.
I will then introduce alternative classes of sources, such as young star clusters and Pulsar Wind Nebulae, that are gaining increasing attention, especially thanks to highlights from very high energy astrophysical observations.
I will finally focus on the latter source class, Pulsar Wind Nebulae, reviewing why and how, in the last decade, they have acquired a central role in Cosmic Ray physics.
