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 was probably built by the people of Byzantine Cappadocia, although the age is uncertain and could be older. The Özkonak Underground City was discovered in 1972 by a local farmer named Latif Acar, who was curious about where his excess crop water was disappearing to. Latif discovered an underground room which, when later excavated, revealed a whole city which could house 60,000 people for up to three months. Although only four floors are now open, the complex contains a total of ten floors, to a depth of 40m. Unlike the other underground cities in this area, there were holes above