London Underground ticketing London Underground ticketing The London Underground metro system of London, England uses a mix of paper and electronic smart-card ticketing. London Underground uses Transport for London's Travelcard zones to calculate fares, including fares on the Underground only. Travelcard Zone 1 is the most central, with a boundary just outside the Circle line and Travelcard Zone 6 is the most outlying zone covering any of Greater London and it includes London Heathrow Airport. All of Greater London is covered by zones 1 to 6. Tickets including zone 1 are usually more expensive than those involving only outer zones. The most popular
Aydıntepe underground city Aydıntepe underground city The Aydıntepe underground city () is an ancient underground city in Aydıntepe district of Bayburt Province, Turkey. It is located northwest of Bayburt beneath a residential area. Discovered by coincidence during excavation works for a building construction in 1988, -to some sources in 1998– the underground city at Aydıntepe features chambers, halls and hallways carved out of volcanic tufa rock formation without using building materials. It is situated under the surface. The chambers and the halls are connected with -wide and -high hallways stretching over about in length. There are eight conical shafts over the hallways, which