Tour of Houses of Parliament in London?

I am going to visit my friend who loves in London this month and I cant wait to go! I have been to London once before a long time ago and I remember wanting to see those impressive Houses of parliament from the inside! I didnt get the chance to do so back then and I would like to make up for that now. Can someone please tell me how to make it happen?

Anyone is allowed in the Houses of Parliament and I remember seeing big cues in order to get in. I am sure there are some organised tours but I am not sure he organises these. I would suggest you to simply turn up at the Parliament and ask one of the people cueing up. If you cant immediately take the tour you can always you and see Whitehall first.