Einstein gave his first lectures on general relativity, in Berlin, in November 2015. This was a seminal piece of work that centered upon gravitational attraction and how mass warps space time. This work led to all kinds of interesting predictions, such as the existence of black holes. In fact some of Einstein’s predictions have still to be verified experimentally, such as the existence of gravitational waves, but is still held in high regard as a theory that has continued to revolutionise our world view.
Einstein has also been credited with some superb social observations that are still as relevant today, as they were when he originally made them.