The London Underground, or "the Tube," is widely considered one of the easiest and most intuitive transit systems in the world, especially for English speakers. Each of the 11 lines is color-coded (e.g., the Central line is red, the Victoria line is light blue), and clear signage in every station directs you toward "Northbound," "Southbound," "Eastbound," or "Westbound" platforms. The digital displays on the platforms show exactly how many minutes until the next train arrives. In 2026, you don't even need to buy a ticket; you can simply "tap in and tap out" using a contactless bank card or a smartphone (Apple Pay/Google Pay), and the system automatically calculates the cheapest fare, including a "daily cap." To make it even easier, apps like Citymapper or the official TfL Go app provide real-time updates and step-by-step directions. While the deep-level stations can involve long walks and the system can be crowded during rush hour, its logic and simplicity make it very accessible for first-time visitors.