The QCD Axion is a Beyond-the-standard-model Curiosity. Originally introduced to solve the strong CP problem, it is effectively described by a one-particle, one-parameter new physics model, and, despite having a mass comparable to the neutrino's, it is a Cold Dark Matter candidate. In the scenario where the axion is born after inflation, I will review the growth of Large Scale Structure in the presence of axion CDM, and speculate about axion configurations in our galaxy today.