History of the London Underground to determine the cause. Following the incident, a system that stops a train automatically if the driver fails to brake was introduced at dead-ends on the London Underground. The Northern City Line was connected to British Rail tracks at Finsbury Park in the 1970s. The last tube train ran in October 1975, and British Rail services began in 1976. In 1977, the Piccadilly line was extended from Hounslow to Heathrow Airport, and in 1986 a platform serving Terminal 4 opened on a loop line. The Fleet line through central London was first proposed in 1965, taking over the Bakerloo line's
Özkonak Underground City Özkonak Underground City Özkonak Underground City is an ancient city built into the northern slopes of Mt. Idis about 14 km northeast of Avanos in Nevşehir Province, in the Central Anatolia region of Turkey. The city has many strata made up of volcanic granite. Its larger areas are connected to each other by tunnels, and it contains a pipe communication system reaching each of its levels. This feature is unique when compared to the Kaymaklı Underground City and the Derinkuyu Underground City. Each carved room had ventilation provided by further piping when the city was sealed during sieges. The city