Henrik Ibsen is one of my favorite playwrights. He’s written A Doll’s House, Hedda Gabbler, An Enemy of the People (my favorite) which is still quite relevant today among many others. I’d say if you are not familiar with his work please read An Enemy of the People.
The Ibsen Museum in Oslo is across from the Royal Palace and attached to an apartment once occupied by Ibsen and his family. At the time of writing (March 2016) there was an instillation about Ibsen and The Beatles and how supposedly Yoko Ono introduced John Lennon who later in turn introduced the rest of The Beatles to Henrik Ibsen and John and The Beatles because influenced by Ibsen.
At the museum you can see some of the clothes once worn my Ibsen, some of his medals (he loved medals you can learn about it on the tour), original playbills, short movies about him, etc. For anyone who loves the theatre in general it’s a lovely thing to see.
You are able to take a free tour of the apartment. (You cannot go into the apartment unless on guided tour) but I thought it was worth it. It was a huge space and you learned many interesting facts. For instance, did you know Ibsen got running water before the Royal Palace across the street?
I’d say you can do the whole museum and apartment tour in 2 – 3 hours if you go in depth, and in less if you just do the highlights. There’s a gift shop and it’s easily walk-able from around Oslo. Check it out before or after the Royal Palace.