Chelsea Physic Garden
Perfectly described by it's claimed intention as a walled secret garden.
Overlooked by traditional English brown brick townhouses. I was jealous of the french windows covered in cushions and rooftops so close by.
Each plant is marked with a plaque describing ancient medicinal uses. Greenhouses. Mediterranean sections, lawns, ponds.
Highly recommended to any Australians currently in London as a cure for homesickness - there are even Eucalyptus trees you can breathe in.