Nationalmuseet is the Danish national museum. Wikimedia Danmark has contact with the museum and the primary wiki-page for the collaboration is Wikipedia Loves Nationalmuseet.
As of summer 2011 Wikimedia Danmark and Nationalmuseet have organized a photo-day, where Wikipedias could take photos and upload it to Wikimedia servers. Users of the museum are allowed to take personal photos within the museum, but not use them commercial. This particular photo-day was an exception. On commons there is a special category for Nationalmuseet  as well as a template for use with pictures taken on the occasion: "nationalmuseet-license"