Constitution Hill is a road in the City of Westminster in London. It connects the western end of The Mall (just in front of Buckingham Palace) with Hyde Park Corner, and is bordered by Buckingham Palace Gardens and Green Park. The term "Hill" is something of a misnomer; there is barely detectable slope but most observers would regard the road as flat. An old lane on this route was enhanced in connection with the development of Buckingham Palace in the 1820s. It formed an official route from the palace to Hyde Park. It is now closed to traffic on Sundays.
The road obtained its name in the 17th century from King Charles II's habit of taking "constitutional" walks there. It was the scene of three assassination attempts against Queen Victoria—in 1840 (by Edward Oxford), 1842 (by John Francis) and 1849 (by William Hamilton). In 1850, the former Conservative Prime Minister Sir Robert Peel was thrown from his horse on Constitution Hill by the gate into Green Park; he suffered a fatal injury and died three days later.
Wellington Arch at Hyde Park Corner was originally the culmination of the route, but the effect is somewhat muted now that the Arch stands at the centre of a busy traffic island. There is a recent war memorial to Commonwealth soldiers near the top of Constitution Hill, just before Hyde Park Corner; the memorial is known as the Memorial Gates.
There are other streets called 'Constitution Hill', for example in Birmingham.