This course is an advanced undergraduate course on monetary economics. We study some empirical facts connecting money, interest rates, inflation, and output growth, as well as models that try to shed light on questions such as: i) why is low inflation desirable?; ii) why do some economies struggle to attain low inflation?; iii) how can we make sense of the effects of monetary policy?; iv) how is monetary policy implemented in a modern economy? Throughout the course, we will make reference to historical episodes of the last four decades, like the Great Moderation, the Great Recession, and the inflation that followed the COVID-19 pandemic, which have generated a continuing debate about the role of monetary policy and its limits.