The metro-project was approved in 1970 and dropped in 1973 because the people of Zurich decided against that project. By that time they'd already build a tunnel next to the Milchbuck-motorway with three stations and a section near Hbf. under an underground shopping mall with the Hbf. underground-station.

The Milchbuck-section was later used for the so called Schwamendingen-tram. The trams had to change from right to left operation in the tunnel because they have only doors on the right side and the stations have only single-platforms. So, the ramps for this tunnel are single-track-ramps one after another to avoid track-crossings at grade. The tunnel was opened in the Mid 80s and the stations have names different from those original planned. They had to develop a new concrete track bed in order to have enough space for a tramway with overhead-wire. The original design for the metro was third rail conduction.
 
The Hauptbahnhof-section was later used for the Sihltal-Uetlibergbahn. It is now part of the S-Bahn-network and uses two or three stations to reach the Hauptbahnhof without any level crossings. It was also opened in the late 80s.

Plans were for one line running from west to northeast and branching of three times in the east.

Stations from west to east:

Dietikon
Schönenwerd
Reitmen
Schlieren
Gaswerk
Farbhof
Altstetten
Kappeli
Letzigraben
Albisriederplatz
Seebahn
Staufacher
Sihlpatte
Hauptbahnhof
Hochschulen/Central
Beckenhof
Schaffhauserplatz
Hirschwiese

From  here one branch along the Milchbuck-tunnel with stations:
Binzwiese
Funkwiese
Hirschen Schwamendingen, probably further into Schwamendingen-area

The other branch towards north:
Bernina
Oerlikon
Eisfeldstraße
Glattal
Oberhausen
Glattbrugg
Werft

From here two branches with just a single station, one to Flughafen and one to Kloten

The streets which are probably planned to put the metro in are from north to south:
Schaffhauserstraße
Stampfenb. strasse
Leonhardstraße, at the ETH (university) truning sharp left
Bahnhofbrücke
following the Sihltalbahn until Stauffacherplatz
Badenerstraße