The Siemens Modular Metro is a family of electric multiple unit trains for rapid transit systems produced by Siemens Mobility (originally Siemens Transportation Systems) and used by rail operators around the world.

[1] Previously known as Modular Mobility, Siemens, whose rail equipment division had since been renamed Siemens Mobility, still uses the abbreviation Mo.Mo;[2][3] however, few of these trains are being built, since Siemens had moved to their Inspiro metro platform in 2013.

Modules in the system include various vehicle ends, doors, gangways, roof-mounted air-conditioning, and interiors.

Stainless steel or aluminium construction is available, in three cross sections: straight sidewalls, sidewalls sloping at 3 degrees, and contoured.

[1] The bodies of the trains evolved from the 1993 DT2 Series used in the Nuremberg U-Bahn whose design in turn came from production of the A Series built for the nearby Munich U-Bahn.