Oulun
Oulun is the genitive form of the Finnish city name Oulu. In Finnish grammar, the genitive marks possession or association, and Oulun appears in many phrases and official titles. It is used to link something to Oulu, for example in Oulun kaupungin hallinto (the administration of the City of Oulu) and Oulun yliopisto (the University of Oulu).
Taken alone, Oulun does not denote a separate place; it functions as part of a noun phrase.
A brief context about Oulu: Oulu is a city in Northern Ostrobothnia, Finland, located at the mouth