An unassuming glass door on an otherwise plain facade hides a cavernous space, with high ceilings and huge sliding partitioned walls producing excellent exhibitions in a space you'll want to go back to.
I grew up in the countryside, and if you're ever in need some instant escape from the city, this place is like a time warp. It's a huge space full of over grown mausoleums and graves, feels like a movie set. They also do tours.
Free natural ponds, open all year round (check online for varying opening hours according to seasons). Get an absolute get away feeling right in the heart of London, a treat if you enjoy swimming with ducks. Amazing park to enjoy a few games of cards and a walk around afterward too...