Mudlarking under the Millennium Bridge

Dating back to the 18th and 19th centuries, when London's poor would search for things to sell, mudlarking is the urban equivalent of beachcombing, and although you're unlikely to find much of value these days, you can easily pick up items that are hundreds of years old. Just don't start digging or you'll need a license - and bring plenty of disposable gloves.

Millennium Bridge, EC4V 3PA.