Cosmic rays with energies up to a few PeV (10^15 PeV) are believed to be of Galactic origin. However, after a century since the discovery, the origin of Galactic cosmic-rays still remains a mystery. In 2016, H.E.S.S. observatory discovered a PeVatron within 10 parsecs from the center of our Galaxy, pointing to the supermassive black hole Sgr A* as a likely candidate. As one of the least active supermassive black holes nowadays, Sgr A* could serve as a powerful particle accelerator during its active stage in the past. In this talk, I am going to outline our efforts on searching for multi-wavelength observational evidence for the Galactic center supermassive black hole serving as a PeVatron. In addition, I will discuss how we can reconstruct the activity history of Sgr A*. Lastly, I will introduce ongoing efforts in discovering and identifying Galactic PeVatrons outside of the Galactic center.