I visited London and this was definitely one of the highlights.
I'm a history buff and so the single thing I enjoyed the most about the trip was visiting the National Museum of History.

The Museum wasn't crowded at all and it was full of historical artifacts and exhibits that I never even dreamed seeing.

I saw the Rosetta stone and was in awe. My girlfriend didn't care about it at all, for her it was just a stone...but for me it was worth the trip... to have that moment.

Cheers. Upvoted!