A great place to start the day if you are in South London is Federation Coffee in Brixton Village. The food is great and so is the coffee. This is a very chilled place where you can get both and indoor and outdoor experience (even though the whole place is under the Village roof).
I worked at the Barbican for several years and during that time became very fond of its architecture. One of my favourite spaces within the centre is the conservatory, a giant tropical garden in the middle of a concrete city.
The Princess Louise, was a Victorian Gin Palace, with mirror and tiles galore, segregated seating and extraordinary urinals. With pints of beer just over £2 you're laughing. It gets packed so we come for a lunchtime pint.