Waterloo and City LineThe Waterloo and City Line is a short underground metro line in London, built in 1898. It has only two stations, Waterloo and Bank, between which it passes under the River Thames. It exists almost exclusively to transport commuters arriving at Waterloo mainline station to the financial district of the City of London (and vice versa), and does not operate on Saturday evenings or Sundays.
Originally part of the London and South Western Railway, it became part of the Southern Railway in 1923, was nationalised with the mainline railways in 1948, and did not become part of London Underground until 1994, when it was sold for the nominal sum of one pound.
It is colloquially known as The Drain. There are two main reasons for this: the smell of the marshy ground on which Waterloo is built, and the drain-like round deep-level tunnels, which were nicknamed "tubes" on the other lines.