Old Street Roundabout is a roundabout located on the boundary of the London Borough of Hackney and the London Borough of Islington. It is an interchange system at the junction of Old Street and City Road. It is sometimes known as St. Agnes Well after the shopping centre beneath it, while the area surrounding the roundabout is often colloquially known as Silicon Roundabout, owing to the prominence of technology companies there.
City Road crosses the roundabout, running south towards the City of London and Moorgate and Liverpool Street stations, and north-west towards Angel, King's Cross, St. Pancras and Euston. The roundabout, the north-western part of City Road, and Great Eastern Street form the boundary of the London congestion charge zone (CCZ).
To the west of Old Street are Clerkenwell, Bloomsbury, and (further afield) the West End. To the east are Shoreditch and London's East End.
The shopping complex in the underpass at the centre of the roundabout is named St. Agnes Well, after an ancient well thought to have been located about 200 metres to the east, at the junction of Old Street and Great Eastern Street. Remnants of the well can be found within Old Street station.
Old Street station is located below Old Street Roundabout. It is served by the Bank branch of the London Underground Northern line and by National Rail Great Northern trains. With the increase in passenger numbers using the station, in 2014 Transport for London announced that it was to offer pop-up retail space at Old Street station as part of a drive to increase its revenue.