line offers a length of 27km with 35 stations, many hours of fun and interesting missions. The Circle Line is an underground service of the London Underground circling the center of London. It was first described as such in 1949 and already appeared on the 1947 Underground Map. It had not been built as a separate line, but was merged from different sections of the Metropolitan Line and the District Line. Only two short sections of this line are solely used by the Circle line.