The Wellcome Collection is a free museum and library, mostly dealing with medecine and social history. The exhibitions are unusual and engaging, and the permanent collection includes bizarre items such as medieval masks and human remains.
Even if you have seen it hundreds of times it will still stop you in your tracks. A great piece of architecture and apparently the largest brick structure in Europe.
The best magazine store in London! MagCulture stocks around 600 independent magazines from all over the world. They always have the latest issue of everything and you will ALWAYS find something you've never heard of before. Make sure you visit on PAY-DAY, as there is a good chance you'll walk away with a delicious new publication.