The London Underground is the world’s oldest subway system, having first opened on January 10, 1863. The original line, known as the Metropolitan Railway, ran between Paddington (then called Bishop’s Road) and Farringdon Street using steam locomotives in gas-lit tunnels. While many think of the "Tube" as a single system, it was actually a collection of separate companies. In 1890, the City and South London Railway became the world’s first deep-level electric "metro" line. In 2026, the London Underground remains a marvel of engineering, successfully integrating these 19th-century tunnels with 21st-century technology like the Elizabeth Line and the latest driverless innovations. While other cities like Budapest (1896) and Paris (1900) followed shortly after, London remains the undisputed pioneer of subterranean urban transit, a legacy that continues to define the city’s geography more than 160 years later.