It is a major district town—a Große Kreisstadt—of the administrative region of Upper Bavaria, about 20 kilometres (12 miles) north-west of Munich.

It was home to many artists during the late 19th and early 20th centuries; well-known author and editor Ludwig Thoma lived here for two years.

The town is known for its proximity to the Dachau concentration camp, operated by Nazi Germany between 1933 until 1945, in which tens of thousands of prisoners died.

Some theories assume the name “Amper” river, which the town lies on, may derive from the Celtic word for “water”.

An alternative idea is that it comes from the Old High German word daha meaning clay, and ouwe, water overflown land.

The first known documentation of Dachau occurs in a medieval deed issued by the Noble Erchana of Dahauua to the prince-bishop of Freising,[3] both descendants of the lineage of the Aribonids.

With this deed, dated to August 15, 805 A.D. (the Feast of the Assumption of the Blessed Virgin Mary), she donated her entire property in Dachau, including five so-called Colonenhöfe and some serfs and bondsman, to devolve to the Bishop of the Diocese of Freising after her death.

During much of the 12th century, Dachau was the primary residence of a smaller branch from the House of Wittelsbach led by Otto I, Count of Scheyern-Dauchau.

Highest elevation of the district is the so-called "Schlossberg", the lowest point is near the neighborhood of Prittlbach, at the border to the next community of Hebertshausen.

The bordering communities are Bergkirchen to the west, Schwabhausen to the northwest, Röhrmoos to the north, Hebertshausen to the northeast, and Karlsfeld to the south.

Coming from Karlsfeld, the Würm crosses Dachau-East and merges into the river Amper just outside the district limit of Hebertshausen.

The Mühlbach, a man made canal, is diverted from the river Amper at the electrical power plant and runs parallel and flows back into it after passing the paper mill.

By allowing it to run to seed and through deliberate cultivation by the town of Dachau the canal is only still recognizable as such between Frühlingstraße and the Pollnbach.

The city is served by Munich S-Bahn (S2) and Deutsche Bahn via Dachau railway station located in the South of the town.