The A406 or the North Circular Road is a road which crosses North London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, UK

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, linking West and East London. It, together with the South Circular Road

A205 road

The A205 or South Circular Road is a direct route which crosses South London, UK, running from Woolwich in the east to the junction of the A406 , the M4 and the A4 at Gunnersbury in the west....

, forms a ring road through the inner part of Outer London

Outer London

Outer London is the name for the group of London Boroughs that form a ring around Inner London.These were areas that were not part of the County of London and became formally part of Greater London in 1965...

. This ring road does not make a complete circuit of the city; being C-shaped rather than a complete loop as the crossing of the River Thames

River Thames

The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 in the east is made on the Woolwich Ferry

Woolwich Ferry

The Woolwich Free Ferry is a boat service across the River Thames, London, UK, which is licensed and financed by London River Services, the maritime arm of Transport for London...

.
In the west, the A406 begins at junction 1 of the M4 Motorway

M4 motorway

The M4 motorway links London with South Wales. It is part of the unsigned European route E30. Other major places directly accessible from M4 junctions are Reading, Swindon, Bristol, Newport, Cardiff and Swansea...

 at Gunnersbury

Gunnersbury

Gunnersbury is a place in the London Borough of Hounslow, with its northern edge in the London Borough of Ealing, west London. It has an area of less than half a square kilometre and is within the west area of the Chiswick W4 postal district of London....

, from which the South Circular Road (A205) heads South over Kew Bridge.