It is a little known fact to most people that the oldest garden in the country is located at the back of Westminster Abbey and is open to the public several days a week. It is an oasis of tranquility at the heart of one of the busiest cities in the world. 
The "Infirmarer's Garden" - as it is officially called - has been in continuous cultivation for 900 years. It was mainly used for growing medicinal herbs, food, fruit and even grape vines for the well-being of the monks. It is still enclosed on two sides by the original medieval wall and its contours are more or less as they were apart from a parcel of land at the north-east end (opposite the Houses of Parliament) that was expropriated by Edward III for his Jewel Tower. 
Dig here and you are digging into the very earth which was Thorney Island, the eyot formed by the convergence of the Thames and the Tyburn on which the Abbey was originally built.
Among the delights of the garden are two mulberry trees and four fading sculptures by Arnold Quellin who was from the studio of the great Grinling Gibbons (1648 – 1721). They were part of an altarpiece made by Gibbons and Quellin for James II as a Catholic chapel for his wife in Whitehall Palace in 1685. The altar piece later became part of the high altar in the Abbey. The statues became surplus to requirements and were moved to the garden where they command an almost metaphysical presence.  Two of them guard the back door to Westminster School and the other two the rear entrance to the garden in Great College Street. 
The garden is open to the public for free several days a week (entrance from Dean's Yard). Here you can experience a rural solitude bang in the centre of London with the Houses of Parliament and the roof of the Abbey in sight. On your way out have a coffee in the Cellarium, an original medieval building, where the monks kept their wine in olden days.