Borough Market around 25474+ times on here already. But I just cannot stop. The place is dangerously close to where I live and so it's become a little impossible to not stop by at least once a week.
The best day is Saturday but you have to get there early-ish so you can check out all the stalls before it's too overwhelming with crowds. The first thing we do is head for Monmouth for the best cappuccinos (and every style of coffee drink) in London. Then we aimlessly stroll around the maze of stalls, tasting all the cheeses, olives, meats and breads. The atmosphere is the best. In the morning it's all about coffee and breakfast, but as soon as it's an acceptable lunch hour you will find people standing around drinking beers and wine, either from the stalls or from the surrounding pubs and cafes.
If you are ever in London, this is one place you have to visit! It's my all time favourite way to start the day!