(no subject)

As part of my efforts to not lose all my Japanese ability, and with the aim of taking this test in December, I'm applying for a ten-week course intended to prepare you for the test. This course is in London on Monday evenings, which means that (as a result of my current working arrangements and a desire to avoid train travel at peak times) I essentially get Monday afternoons in London for free. This seems like an opportunity to do some of the Cultural things I never get round to doing because they don't quite seem worth a special trip into the capital.

So, does anybody have any suggestions for Interesting, Improving or Idiosyncratic things to do in London? Somebody's suggested the British Library; I was wondering about climbing the Monument. What else?