Sagene is a borough of the city of Oslo, Norway. The area became part of the city of Oslo in 1859. The name Sagene itself is the plural of the Norwegian word for "saw", reflecting all the old industrial mechanical saws powered by the river Akerselva in this area in the 19th and early 20th centuries.

Akerselva or Akerselven is a river which flows through Oslo. It starts at Maridalsvannet in Oslomarka, and traverses the boroughs of Nordre Aker, Sagene, Grünerløkka, central Oslo and Grønland, whereby it finally ends at Paulsenkaien and Oset in Bjørvika. The river is considered to be a part of the Nordmarkvassdraget, and has the Norwegian watercourse number 006.Z. The entire river is about 9.8 kilometres (6.1 mi) long, and has a difference in elevation between source and mouth of approximately 149 metres (489 ft).