Epsom became a spa in the early 17th century when a spring containing Epsom salts was discovered on the Common. Its popularity with London society brought visits from Samuel Pepys and Nell Gwynne, the development of shops and inns and the oldest spa assembly rooms in England. This stands at the western end of Epsom High Street. Horse racing on Epsom Downs began during the spa period, but it was not until the Oaks was run in 1789 and the Derby the following year that it took on its present form. The first grandstand was built in 1830 and Queen's Stand in 1995. The 1927 grandstand was demolished in 2007/8 and the new Duchess's Stand opened in its place in 2009.