Chelsea Physic Garden

Founded in 1673, this is not the oldest botanical garden in England (Oxford Botanical Garden got a three-year head start), but it does contain the oldest rock garden, made from fused bricks and flint, stones from the Tower of London, and Icelandic lava brought up the Thames by ship in 1772. As well as being crucial for the transportation of both plants and botanists, the garden's proximity to the Thames ensured that it enjoyed a microclimate that made it possible to grow non-native plants, including the largest outdoor fruiting olive tree in England. Today the garden is home to Britain's first garden of ethnobotany (the study of the botany of different ethnic groups and indigenous peoples). The garden is open Wednesday, Thursday, Friday, Sunday and bank- holiday afternoons from April to October, with late openings on Wednesdays. There's a shop where visitors can buy unusual plants and a café that serves very good homemade cakes.