Central line (London Underground) and Great Eastern Railway buildings east of , from when the line to Epping was a rural branch line. In terms of total passengers, the Central line is the busiest on the Underground. In 2011/12 over 260 million passenger journeys were recorded on the line. It currently operates the second-most frequent service on the network, with 34 trains per hour (tph) operating for half-an-hour in the westbound direction during the morning peak, and between 27 and 30 tph during the rest of the peak. This makes the Central line the busiest and most intensively-used railway line in the United Kingdom:
London a major international air transport hub with the busiest city airspace in the world. Eight airports use the word "London" in their name, but most traffic passes through six of these. Additionally, various other airports also serve London, catering primarily to general aviation flights. The London Underground, commonly referred to as the Tube, is the oldest and third longest metro system in the world. The system serves 270 stations and was formed from several private companies, including the world's first underground electric line, the City and South London Railway. It dates from 1863. Over four million journeys are made every