Bülach (Alemannic German pronunciation: [ˈbylɑχ]) is an historic town and a municipality in Switzerland in the canton of Zürich. It is the administrative capital of Bülach district. It is situated in the Glatt Valley (German: Glattal) to the east of the small river Glatt and about 4 km (2.5 mi) south of the High Rhine and about 6 km (3.7 mi) north of the Zurich Airport. The official language of Bülach is Swiss Standard German, but the main spoken language is the local variant of the Alemannic Swiss German dialect.