Mind the gap! The London Underground is the world's oldest underground system and covers most of Greater London. Although it is called the Underground, about 55% of the network is actually above ground. It has 275 stations and 12 interconnecting lines. Each line has a name and a colour to represent it on the underground map. for example the Victoria Line is blue. The London Underground is also one of the longest underground systems in the world, with over 408 kilometres of track. Its first passenger trains started running in 1863, on the Central Line, and today three million passengers travel on it every day. Londoners call the Underground "the Tube', after its tube-shaped tunnels. During the Blitz, the aerial bombing of London in World War II, Londoners hid from the bombs by using the underground stations as shelters during air raids and slept on platforms overnight. Air-raid sirens were a signal of approaching planes and for Londoners to go down to the stations. The Underground does not run 24 hours a day. Track maintenance is done at night, after the system closes. The first trains start operating shortly after 5 a.m. running until around I a.m.: rush hour is from 7:30 to 9:30 in the morning, and from 4.30 to 6.30 in the evening. London is divided into six travel zones. Zone one is the most central zone and zone six is the outer zone which includes Heathrow Airport. The more zones you cross, the more you pay on the Underground. To travel on the Underground, you can buy a daily ticket, a daily travel card, or an Oyster card. This is a smart card with an electronic chip that you charge with credit, and use to pay for travel on the Underground and on buses. It is the cheapest way of travelling in central London. Some Underground stations have lifts; most have escalators and stairs. The longest escalator in Europe is at Angel station on the Northern Line: it is 60 metres in length, with a vertical rise of 27.5 metres. People using the escalators stand on the right-hand side, so those in a hurry can walk past them on the left. There are several safety announcements given to passengers who travel on the Underground. When the doors of the trains are about to close, you hear 'stand clear of the doors please'. When the train stops in a station where there is a gap between the train and the platform you will hear the famous phrase, "Mind the gap!". Find the words in the text that mean: I time when many people are going to or from work (2 words) 2 place where trains stop 3 an upward movement 4 people who are travelling by train 5 the complete system of lines 6 moving stairs that take people up and down 7 one every day 8 Underground route 9 machine that carries people straight up or down 10 local name for the London Underground Il metal lines that trains travel on 12 make journeys (train) 13 area of the city 14 long hole under the ground