The Wellcome Collection is a 5 min walk from Kings Cross or Euston and has lots of free events/exhibitions and tours. It is part of the Wellcome Trust, a large charity that funds biomedical research.

Here you will find a cafe, bookshop and temporary exhibitions on the ground floor as well as permanent exhibitions and a library upstairs. When I was there, after venturing upstairs I found a wall where you can add your own drawing on the back of a large postcard that gives you a choice of words as inspiration. Or you could add your biometric data to a touch screen that creates your own personal pattern from your height, fingerprint and heart beat.

For more details visit:

http://www.wellcomecollection.org/exhibitionsandevents/index.htm