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.
Nice old trees, lots of space, good for walking, running, hanging out with your kids and most of all, the perfect place to lie in the grass and chill out.
Spring always arrives earlier to London, and London shows its most beautiful face during the spring. If you live in London, or if you come to visit, bring your training shoes and take a morning run along river Thames in Chiswick. Between Barnes Bridge and Hammersmith Bridge, there's a great trail on both sides of the river. And if you take the run in March, you might run through this wonderful Alice-in-Wonderland cherry-blossom landscape.