While large Earthquakes could have devastating effects on humankind, they also provide information about the Earth’s internal structure. In this talk I will illustrate how we have come to know about the Earth’s interior. Did you know that a metallic fluid core underlies a solid rocky mantle, and how deep this transition occurs? Did you know that a female seismologist was responsible for discovering that near the centre of the Earth was a transition from a fluid back to a solid?