While in London I visited the Churchill War Rooms - a museum dedicated to the underground bunker that Churchill and the British government used during WWII. This museum was recommended to me by family friends and I have to say it was a good fit.
Before and after going here I heard wonderful things about the museum and it was wall set up. I will caution thought that I was by far the youngest person going through the museum, I think everyone else had lived through WWII.
The set up of the museum gave an idea of what it would have been like to be down in the bunker for long periods of time (I work in an office without windows so I undertood that part of it already). there was an authentic feel to the museum with the use of actually and period pieces. The only thing I didn't like was that some of the maniquines made the museum feel a little cheesy.
I would recommend this musuem to others visiting London, particularly if you are interested in history. I'm not sure I would put it on a 1 day itinerary, but probably a 2 or 3 day + itinerary. There was another part to the museum, about Churchill himself. I opted to skip that part as I was getting hungry and he wasn't my primary interest in visiting.