Public holidays include: New Year's Day, Easter, Ascension Day, Pentecost, and Christmas.
According to the Act on Public Holidays and Holiday Peace (in Norwegian), access to the buildings is not permitted in connection with extraordinary activities such as seminars, conferences, or student social events on these days. This also applies to the days during Easter and between Christmas and New Year's Eve.
Events related to May 1st and May 17th are permitted to a limited extent upon application to postmottak@eiendom.uio.no.
The university museums have their own rules and opening hours.