Designed by John Nash in 1827 and based on the Arch of Constantine in Rome, Marble Arch was used as a monumental entrance to Buckingham Palace until 1851, when it was transferred to its current location on the north-eastern corner of Hyde Park. A small river, the Tyburn, flowed there in olden times, but is now filled in. On its banks stood the Tyburn gallows, where public hangings took place until 1783.