City and South London Railway The station was opened on 17 November 1901 as an extension of the
City and South London Railway (C&SLR), the first deep-level tube railway in London that connected the
City of London with
Southwark. It was part of an extension from
Moorgate to
Angel, along with the station at City Road. The area around the station was originally a mix of light industry, commerce and warehouses. The Northern City Line platforms were opened on 14 February 1904 by the Great Northern & City Railway, which built its tunnels to a diameter capable of accommodating main-line
trains as it was intended to carry such services from its northern terminus at the
Great Northern Railway's
Finsbury Park station to Moorgate. Before Moorgate was expanded in 1938 to include in-station escalators between platforms, Old Street was used as the main interchange between the C&SLR and the Northern City lines. The Finsbury Park connection eventually opened in November 1976, with the line becoming a
British Rail route, with through services to
Hertford and . The C&SLR was built with smaller tunnels than the later tube lines and needed to be enlarged to enable them to accommodate standard stock trains. The section between Euston and Moorgate closed on 8 August 1922 and reopened on 20 April 1924. The surface building was rebuilt in 1925 when escalators replaced the lift shaft to access the platform tunnels. The station frontage was redesigned by the
Underground Electric Railways Company of London's architect
Stanley Heaps with consultant architect
Charles Holden. Holden had been recommended by managing director
Frank Pick to make uniform facades for several station entrances. He designed the stations for the C&SLR's extension to
Morden which was being built. Old Street was used as a bomb shelter during
World War II; the nearby City Road station (which had closed in 1922) was temporarily re-opened to use as a shelter.
Reconstruction In 1968, the station was again modified; the surface building was replaced with a sub-surface structure in the centre of the roundabout and another escalator shaft was added. During the 1990s corrosion caused by excessive soil acidity required a section of the
cast iron running tunnel lining in the Northern line, south of Old Street, to be relined with
stainless steel tunnel segments. In the early 1970s, Old Street was planned to be a stop on a
new tube line from Wimbledon in the southwest to Leytonstone in the northeast, via Waterloo and Holborn. The route incorporated parts of existing lines at each end but was not built because of a lack of funding. In 2014 the station was redeveloped in a collaboration between
Transport for London and letting agency Appear Here.
Pop-up retail spaces were constructed around the station entrance in a drive to increase revenue. Old Street station has had increased footfall in the 21st century. In 2014, around 23 million people passed through the station annually. The station is considered strategically important, as the area around Old Street is being developed as a centre for
Information Technology. In 2017, the London Borough of Islington announced plans to redevelop the area around the station with a new entrance and better facilities for cyclists. ==Incidents==