Great place to work and even better coffee. The roastery at the ground floor gives off a nice scent that fills the whole space. Sit near the bar at the kitchen area and look at all the delicious stuff the chefs whip up - and try their V60!
I love the architecture of the Barbican - it is so important to its historical context, at a time when London was being shaped for modernity after the war - they also aspired to make it a bold art centre. We need bold, always.
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).