The Universe is full of fascinating objects with conditions that we will never be able to reproduce in terrestrial laboratories. With astronomical observations, we are able to explore this Universe and to test some of the fundamental laws of nature that we determine here on Earth. Are these laws indeed the same everywhere, even around black holes? In other words, is Einstein’s theory of gravity the final word on our understanding of gravity, or was he wrong? This talk will describe some of the experiments done by astronomers to test Einstein’s theory – using objects or methods that Einstein had no knowledge of. Surprisingly, some of the findings even affect our daily life.