The Marble Arch was originally constructed to stand proudly in front of Buckingham Palace. However, in 1851, when the palace expanded, the arch needed to find a new home. It was relocated to its current spot at Hyde Park, where it stands today.
Though it now sits on a bustling traffic island, Marble Arch is still a notable landmark. Its location might seem a bit isolated, surrounded by the constant flow of vehicles, but modern conveniences make it easily accessible. A subway beneath the busy roads allows pedestrians to visit the arch effortlessly.
For those journeying from Oxford Street to Hyde Park, a stop at Marble Arch provides a moment to appreciate this historical structure. Despite its journey from palace grounds to its current setting, the arch remains an interesting piece of London's architectural heritage.
Source - https://en.wikipedia.org/wiki/Marble_Arch