The Parliament of Norway (called Stortinget in Norwegian) was designed by the Swedish architect Emil Victor Langlet and the politicians of Norway has been in this building since 1866. It is located by the Karl Johans Avenue. There are 169 members in the Norwegian Parliament. If you have travelled some around the world you have probably seen nicer parliaments than this one, but it is still worth taking a look at the Norwegian Parliament as you visit Oslo.
Karl Johans gate 22
Norwegian Parliament pictures