The M25 or London Orbital Motorway is a 117-mile (188 km) motorway that encircles almost all of Greater London, England (with the exception of North Ockendon), in the United Kingdom. An ambitious concept to build four concentric ring roads around London was first rooted in the 1960s. A few sections of the outer two rings were constructed in the early 1970s, but the plan was abandoned and the sections were later integrated to form a single ring which became the M25, aka London Ring Road, finally completed in 1986.
The M25, plus the short non-motorway A282 which joins the two ends of the M25 across the River Thames using the Dartford Crossing, is Europe's second longest orbital road after the Berliner Ring, which is 122 miles (196 km).
