In the aftermath of the attack, it became clear that the city's existing defences weren't effective and therefore, a stronger defensive centre was needed.

(This battle forms a major part of the plot of Sigrid Undset's historical novel In the Wilderness, the third volume of her tetralogy The Master of Hestviken.)

Akershus was besieged yet again in 1523, this time by Swedish soldiers but Oslo's inhabitants, at the command of Hans Mule, burned down their houses in an attempt to drive them out and the Swedes retreated after a short period.

In 1567, during the Northern Seven Years' War, the castle was besieged once more by Swedish forces, but the Danish-Norwegian king's lord lieutenant, Christen Munk, responded by burning down the city in order to deprive the attackers themselves of the means of receiving supplies, and eventually the Swedes retreated.

However it surrendered without combat to Nazi Germany in 1940 when the Norwegian government evacuated the capital in the face of the unprovoked German assault on Denmark and Norway (see Operation Weserübung).

In September 1589, Anne of Denmark tried to sail to Scotland when she was betrothed to King James VI, but after difficulties with her ships and weather, she made her way to Akershus with the Scottish Earl Marischal.

[9][10] After they married, when they were at Elsinore (Kronborg), a servant of Axel Gyldenstierne, captain of Akershus, was rewarded for bringing letters to the Scottish king.

The castle primarily functioned as a palace until the turn of the 19th century, with new towers, halls, chambers and gates being added over time.

Particularly well-known people to have been imprisoned there include author Gjest Baardsen (1791–1849), and the similarly idealized thief Ole Høiland.

Following the 1852 Laestadian Sámi revolt in Guovdageaidnu, all men except the two leaders Aslak Hætta and Mons Somby (who were beheaded in Alta) ended up in Akershus Fortress – the women were imprisoned in Trondheim.

Since restoration of the main building, the castle has frequently been used as the venue for official events and dinners for dignitaries and foreign heads of state.

Walt Disney World in Bay Lake, Florida just outside Orlando in the United States replicates a portion of the fortress at the Norway Pavilion at its Epcot theme park.