NIKU has conserved the mural paintings in Oslo City Hall. The paintings are in good condition, but the lower wall sections were inflicted by damage after visitor wear.

These areas were retouched. On one wall there had been large cracks which were repaired. Rinse samples were also taken, but NIKU did not recommend a general clean up, because it would have been too much strain for the paintings

The assignment from Oslo Municipality also included proposals for preventive measures and guidance on the proper use of the rooms. NIKU recommended physical barriers in some areas to better protect the paintings. In addition, NIKU recommends regular maintenance where a conservator treats damage that may occur from time to time.

The Oslo City Hall was built after drawings by Arnstein Arneberg and Magnus Poulsson, architects during the 1930s, and opened in 1950. The Rådhushallen and the three galleries on the second floor are adorned with murals painted by contemporary renowned Norwegian artists: Alf Rolfsen, Alex Revold , Per Krogh and Åge Storstein.