Airports of London cannot be expanded due to the docks on either side. It is also the only airport serving London which does not operate at night. A light rail service from London City Airport DLR station, which adjoins the terminal building of London City Airport, links it to the financial district of the City of London at Bank and Monument stations, which offer interchanges with London Underground. Located in the London Borough of Hillingdon, Heathrow is by far the largest of London's airports and considered the main gateway into the United Kingdom for non-European visitors. Heathrow has four terminals and two parallel
London Underground 1972 Stock London Underground 1972 Stock The London Underground 1972 Stock is a type of rolling stock used on the London Underground. The 1972 Stock was ordered to make up the shortfall in trains on the Northern line's 1959 Tube Stock fleet. It is, however, currently used on the Bakerloo line. Following the withdrawal of the A Stock on the Metropolitan line in 2012, and the C Stock on the Circle, District and Hammersmith & City lines in June 2014, these trains are now the oldest trains on the London Underground and also on any rapid transit system in the United Kingdom.