History M25, Grays Essex England

At 117 miles, the M25 or London Orbital Motorway is the longest city bypass in the world. Its radius varies from 13 to 22 miles from Charing Cross. Most London roads are managed by Transport for London but as part of England's strategic road network, the M25 is managed by the Highways Agency. 

A Royal Commission first suggested a ring road for London in 1905 but only parts of the planned road were created at that time. By the 1970s, the huge growth of motor traffic had led to firm Government plans for what became the M25. The last 13 miles from Micklefield to South Mimms opened ahead of schedule in October 1986 by then Prime Minister Margaret Thatcher.