Explore the intricacies of general relativity in this 50-minute lecture, the third installment of a series presented by Peter C. Aichelburg and Piotr T. Chruściel at the Erwin Schrödinger International Institute for Mathematics and Physics (ESI). Delve into advanced concepts of Einstein's groundbreaking theory as part of the Thematic Programme on "Geometry beyond Riemann: Curvature and Rigidity." Gain insights from renowned experts in the field, expanding your understanding of the mathematical foundations and physical implications of general relativity. Note that while this lecture is publicly available, Lectures I and VI by Prof. Aichelburg are not accessible due to copyright restrictions.