The ability to evolve and adapt is a fundamental property of living systems. In many populations, the process of adaptive evolution can be thought of as an uphill walk of a population on a "fitness landscape" where mutations are steps and fitness is altitude. Understanding the structure of fitness landscapes is a fundamental open problem in evolutionary biology. I will discuss our efforts to probe the fitness landscapes and the adaptive walks on them using experimental microbial populations. I will show some interesting and perhaps somewhat counter intuitive patterns that we found. If time permits, I will say a few words about our initial attempts to build a theory that might help us understand these patterns.