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
Özkonak Underground City the tunnels used for dumping hot oil on the enemy. Just like Kaymaklı and Derinkuyu, Özkonak has a water well, ventilation system, winery and moving stone doors. 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