Not the most exciting place inside, but a lovely rooftop area which not all that many people seem to know about, 2 mins walk from Old St station. If it’s packed then The Red Lion is just up the road.
This is an amazing place for the summer when the water gets pretty warm or the winter if you are very brave. The only downside is that it can get very crowded in the Mixed pool but the men’s pool is normally quiet and it has a diving board.
A place that really grows on you, with each visit the Barbican reveals more of itself to you and your bond is tightened. The Barbican Kitchen is great for coffee or lunch, summer hangouts by the ponds, cinema in winter, the amazing Barbican Hall for live music, and don't miss the conservatory.