Zédel is my absolute favorite restaurant in London. Beside the fact that I love french cuisine, Zédel is aesthetically pleasing, very reasonably priced, is good for any occasion, and of course - delicious. My favorite is the bouillabaisse and a bottle of the Bordeaux Superior.
The Greenwich Observatory with its green laser beam can transfigure any night sky. If you decide to cross the Thames via the foot tunnel, make sure you look out for the green ray. You can be on one side of the meridian in a minute, and cross to the other side on the next, without even realising it.
Founded in 1828 the museum houses around 67,000 specimens many of which are now extinct or endangered. My favorite is the skull of a Bottlenose Whale from 1860.