The urban district 11 in the north of Zurich, behind the two hills Käferberg and Zürichberg is often referred to as Zurich Nord. The villages Oerlikon, Affoltern, Seebach merged with Zurich in 1934. Close to the airport, Oerlikon is home to numerous companies today, and to Zurich’s biggest event hall Hallenstadion and the trade fair grounds. Lots of housing, offices, parks and hotels have been built here in the past five years.