The previous boundaries of the city of Zürich (before 1893) were more or less synonymous with the location of the old town. Two large expansions of the city limits occurred in 1893 and in 1934 when the city of Zürich merged with many surrounding municipalities, that had been growing increasingly together since the 19th century. Today, the city is divided into twelve districts (known as Kreis in German), numbered 1 to 12, each one of which may contain anywhere between 1 and 4 neighborhoods:
District 1, known as Altstadt, contains the old town, both to the east and west of the start of the Limmat river.
District 2 lies along the west side of Lake Zurich, and contains the neighbourhoods of Enge, Wollishofen and Leimbach.
District 3, known as Wiedikon is between the Sihl river and the Uetliberg, and contains the neighbourhoods of Alt-Wiedikon, Sihlfeld and Friesenberg.
District 4, known as Aussersihl lies between the Sihl and the train tracks leaving Zürich Hauptbahnhof.
District 5, known as Industriequartier, is between the Limmat and the train tracks leaving Zürich Hauptbahnhof, it contains the former industrial area of Zürich which has gone under a large-scale rezoning to create upscale modern housing, retail and commercial real estate.
District 6 is on the edge of the Zürichberg, a hill overlooking the eastern part of the city. District 6 contains the neighbourhoods of Oberstrass and Unterstrass. There neighbourhoods are home to Zürich's wealthiest and more prominent residents.
District 7 is on the edge of the Adlisberg hill as well as the Zürichberg, on the eastern side of the city. District 7 contains the neighbourhoods of Hottingen and Hirslanden.
District 8, known as Riesbach, lies on the eastern side of Lake Zurich.
District 9 is between the Limmat to the north and the Uetliberg to the south. It contains the neighbourhoods Altstetten and Albisrieden.
District 10 is to the east of the Limmat and to the south of the Hönggerberg and Käferberg hills. District 10 contains the neighbourhoods of Höngg and Wipkingen.
District 11 is in the area north of the Hönggerberg and Käferberg and between the Glatt valley and the Katzensee (Cat's Lake). It contains the neighbourhoods of Affoltern, Oerlikon and Seebach.
District 12, known as Schwamendingen, is located in the Glattal (Glatt valley) on the northern side of the Zürichberg.
Most of the district boundaries are fairly similar to the original boundaries of the previously existing municipalities before they were incorporated into the city of Zürich.