Special Places to Visit in London?

I am going to London in March for a week vacation. I was there last year and managed to see all the high lights (London Eye, Tower, Soho, Greenwich, Canary Wharf, Little Venice, Camden Town etc.), now I am looking for some really interesting things and places to visit. What are your suggestions? (for example is there a really interesting pub or Cafe, or even maybe open air swimming pool with hot water?)