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.
You could call me biased, given this is the 3rd Highbury restaurant in my list, but if you're doing so then you've clearly never tried the Biang Biang Noodles at this unassuming little BYOB gem