Explore the fascinating intersection of geometry and relativity in this 59-minute lecture on the Global Positioning System (GPS). Delve into the satellite setup, cesium atomic clocks, and the geometric principles behind determining location using four satellite positions. Discover the historical precursors to GPS, including LORAN and World War I audio systems. Examine the crucial roles of Einstein's Special and General Theories of Relativity in ensuring GPS accuracy, with simplified explanations of key concepts like the Michaelson-Morley experiment, the constant speed of light, and the Equivalence Principle. Learn how relativistic effects impact atomic clocks in GPS satellites and why engineers must account for these phenomena to maintain system precision.