Learn more about Marble Arch
Marble Arch is a white Carrara marble monument near Speakers' Corner in Hyde Park, at the western end of Oxford Street in London, England, near the tube station of the same name. Only members of the royal family and the King's Troop, Royal Horse Artillery are allowed to pass through the arch.
In 1828, John Nash designed the arch based on the triumphal arch of Constantine in Rome. It was originally erected on The Mall as a gateway to the new Buckingham Palace (rebuilt by Nash from the former Buckingham House).
In 1851, the arch was moved to its present location during the building of the east front of the Palace.
The arch might eventually be moved back to either its original or else a different location. (There is no truth in the often-repeated story that the Arch was too narrow for the state coach, which passes freely through the Arch as was seen during the coronation procession of Queen Elizabeth II in June 1953.) 
There are three small rooms inside that were used as a police station until 1950, first for the royal constables of the Park and later the Metropolitan Police. One policeman stationed there during the early 1860s was Samuel Parkes who won the Victoria Cross in the Charge of the Light Brigade in 1854.
Some sculptures intended for the arch ended up on the façade of the National Gallery due to Nash's financial problems. In particular are those high up on the east façade, opposite the Edith Cavell memorial (Britannia) and above the old main entrance under the portico. These last two were originally intended to represent the campaigns of the Duke of Wellington, these sculptures include reclining personfications of Europe and Asia/India, with a blank roundel in between. Had the arch been completed as planned, the Duke of Wellington's face would have been depicted in the roundel.
Britannia, now Minerva, patroness of the arts
The area around the arch forms a major road junction connecting Oxford Street to the east, Park Lane (A4202) to the south, Bayswater Road (A402) to the west, and Edgware Road (A5) to the north-west. The short road to the north of the arch is also known as Marble Arch.
The area once was home to the largest cinema screen in London, the Odeon Marble Arch. Originally 18 meters (60 feet) wide, the Odeon showcased 70 mm films. The cinema was converted into a mini-plex in the mid 1990s.