The Circle Line is a circular railway line in the London Underground system, primarily serving central London. It connects several key areas, including Paddington, Baker Street, and Tower Hill, allowing passengers to travel around the city without needing to change lines frequently. Opened in 1884, the Circle Line is known for its distinctive yellow color on the Tube map. It covers approximately 17 miles and has 36 stations, making it a convenient option for both commuters and tourists exploring the city's attractions.