The District line is a line of the London Underground, coloured green on the Tube map. It is a “sub-surface” line, running through the central area in shallow cut-and-cover tunnels. It is the busiest of the sub-surface lines and the third busiest overall on the Underground network.
The District line was built by the Metropolitan District Railway (MDR) and opened in stages from 1868.
The London Underground is a rapid transit system serving a large part of Greater London and neighbouring areas. Despite the name, about 55% of the network is above ground. It is usually referred to officially as ‘the Underground’ and colloquially as the Tube.
The nickname “the Tube” comes from the circular tube-like tunnels through which the trains travel and within which the station platforms are built.
“Please Mind The Gap between the train and the platform. Mind the Gap!”
Tower Hill is a London Underground station at Tower Hill in the London Borough of Tower Hamlets. The entrance to the station is located a few metres from one of the largest remaining segments of the Roman wall which formerly surrounded what is now the City of London.
It replaced a station with the same name, but earlier called Mark Lane tube station, that was farther west.