London

So I'm going to London in a few weeks. The trip is techmically my sister's high school graduation gift from my parents and I'm just going along. I get to pick like one thing that I want to do and the rest is up to my sister and my mom. We are already going to the london eye, having tea on a boat, going to the Victoria and Albert Museum, going to one of the gardens, and going to the duke of york square. Any other suggestions? I found many places I like but I need to narrow it down.