page_title: A1 in London
section_title: Route
hierarchical_section_title: A1 in London / Route
caption_attribution_description: Routes of the A1 and A1000 roads within Greater London, with London Borough boundaries
context_page_description: The A1 in London is the southern part of the A1 road. It starts at Aldersgate in the City of London, passing through the capital to Borehamwood on the northern fringe of Greater London, before continuing to Edinburgh. The road travels through the City and three London boroughs: Islington, Haringey and Barnet, which include the districts of Islington, Holloway, Highgate, Hendon and Mill Hill, and travels along Upper Street and Holloway Road, crossing the North Circular Road in Hendon, a district in the London Borough of Barnet.
  The A1 is the most recent in a series of routes north out of London to York and beyond. It was designated in 1921 by the Ministry of Transport under the Great Britain road numbering scheme, comprising existing roads and streets, mostly historic, and later using stretches of purpose-built new roads in what is now the outer London borough of Barnet. The Archway Road section was built by Thomas Telford using Roman cement and gravel, an innovative technique that was used there for the first time, and is the basis for modern road building.
context_section_description: The route of the A1 in London runs from the northern end of St. Martin's Le Grand in the City to Borehamwood in Hertfordshire, then travels on the northern fringe of Greater London to Bignell's Corner, where it crosses the M25 and becomes a motorway, designated A1(M), which alternates with the dual carriageway A1 as it continues to Edinburgh. The London section of the road passes through part of the City of London and three London boroughs: Islington, Haringey and Barnet. The A1 is one of London's main northern routes, providing a link to the M1 motorway and the A1(M) motorway, and on to the Midlands, Northern England and Scotland. It connects a number of major areas within London, and sections of it serve as the High Street for many of the now-joined villages that make up north London. Even though it is one of London's major roads, less than 5% of its approximate 60,000 vehicles a day are through traffic – the bulk is local.
  The current start of the A1 is the modern roundabout at the northern end of St. Martin's Le Grand where it meets Aldersgate Street, near the site of the now demolished General Post Office, London, the headquarters of the Post Office from 1829 to 1910. When originally designated in 1921 the A1 started a little further north along Aldersgate Street at Aldersgate Bars, which marked the boundary of the City, though some later maps indicate it starting at the southern end of St. Martin's Le Grand, near St Paul's Cathedral.  The route runs north from Aldersgate along Aldersgate Street which is a modern dual carriageway, and from the 13th century was known as a wide street with fine buildings and travellers' inns; these were destroyed or badly damaged during the Blitz, and from 1965 to 1976 the 40 acre (162,000m²) Barbican Estate, an arts complex and residential estate, was constructed along the entire eastern side of the street. At the end of Aldersgate Street stood Aldersgate Bars, which marked the limits of the City of London.
caption: The current route of the A1 (red) and the historic route of the Great North Road (blue)
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