Victor F. Hess, in 1912, in an attempt to find the cause of ionization in his hermetically sealed vessel, demonstrated the existence of highly penetrating radiation of extraterrestrial origin through a series of balloon flights. He received the Nobel Prize in Physics in 1936 "for his discovery of cosmic radiation" (The Nobel Foundation, 1936). This discovery opened up a new field of astroparticle physics and lead to the discovery of several fundamental particles and improved our understanding of particle interaction at highest energies. This symposium will review and highlight important discoveries and unanswered questions in the past 100 years. We will revisit the Indian contribution to Cosmic Ray research and highlight a few of the results.