The Waterloo & City line is the shortest underground railway line in London; it is the least used line on the Transport for London Underground network, carrying around 15 million passengers annually. It has only two stations, Waterloo and Bank, and it passes under the River Thames.
Its primary traffic is commuters to the City of London travelling from the South West of England via Waterloo mainline station, and for this reason it does not normally operate on Sundays or public holidays.
It was opened on 11 July 1898, having been built by the Waterloo & City Railway Company. Bank station is within the City of London, and was originally named "City". It is by far the shortest line on the London Underground, at 2.37 km (1.47 miles), and it takes only four minutes to travel from end to end. It was the second electric tube railway to open in London, after the City and South London Railway (now part of the Northern line). It was incorporated into the London Underground network, being transferred from British Rail ownership in 1994.