Akershus is a former county in Norway. It was bordered by Hedmark, Oppland, Buskerud, Oslo and Østfold; the area has a short border with Sweden. Akershus was the second largest county in population after Oslo. It has more than half a million people living in it. The county was named after Akershus Fortress. The county administration was in Oslo, which was not part of the county.
On 1 January 2020 the county merged with Buskerud and Østfold to the current county of Viken.