Marble Arch

Marble Arch is a white Carrara marble monument which is on a large traffic island. It is at the junction of Oxford Street, Park Lane, and Edgware Road, almost directly opposite Speakers' Corner in Hyde Park in the City of Westminster, London.
Historically, only members of the royal family and the King's Troop, Royal Horse Artillery, have been allowed to pass through the arch in ceremonial procession.
The name "Marble Arch" today usually refers to the area in West London where the arch is, at the southern end of Edgware Road. There is also a Marble Arch underground station nearby.
History.
Until 1851 it stood in front of Buckingham Palace. The arch was designed in 1825 by John Nash as a ceremonial entrance to the courtyard of the new Buckingham Palace. He was rebuilding the palace from the former Buckingham House. The palace, as designed by Nash, was laid out around three sides of the courtyard, with the Marble Arch placed on its open eastern side.