My office used to be in Leadenhall Market and it is like a small community. I still work nearby and I love the Buzz in Leadenhall Market as there is always something going on albeit the flea market or the celebrity signing in Waterstones Bookshop - or the evening events. Best time is near Christmas when the London Mayor comes along to turn on the Christmas Tree lights and there is carol singing and lots of mince pies and drinks flowing. The best place to get a taste of London.