The M-30 orbital motorway circles the central districts of Madrid, the capital city of Spain. It is the innermost ring road of the Spanish city. Outer rings are named M-40, M-45 and M-50.

It has, at least, three lanes in each direction, supplemented in some parts by two or three lane auxiliary roads. It connects to the main Spanish radial national roads that start in Madrid.

The M30 is the busiest Spanish road, famous for its traffic jams, and surrounded by several landmarks such as Torrespaña (the former tallest structure in Madrid, as of 2010 the tallest structures in Madrid are the 4 towers built in the financial district, north of torrespaña), the national headquarters of IBM, and passes under the Vicente Calderón Stadium.

Its construction started in the 1960s and required the underground canalisation of the Abroñigal river, required to avoid flooding since the road runs through the lowest part of the city. In the 1970s the most important section was open between the junction of Manoteras (cross with the A-1, M-11 and accesses to Sanchinarro) and the Nudo Sur (South Junction), that connects to the Avenida de Andalucia (previously N-IV) and A-4.