Famously, only members of the royal family are permitted to pass through Marble Arch, which is an actual arch near Hyde Park. It was originally erected on The Mall, but was then moved to its present location near Speakers Corner. Interestingly, there are three tiny rooms inside Marble Arch that were used as a police station up until 1950.
It received a renovation that cost 75,000 pounds in 2004, and for many years it has been seen as something of a white elephant, with many people wondering just when it might be moved back to The Mall, or even somewhere else. Since no one can use it unless they are blue-blooded or part of the armed forces, it stands there just to be looked at rather than touched or actually entered. The fact that it was originally built as the entrance to Buckingham Palace and then moved because it was apparently too small has given weight to the theory that the Mall could be welcoming it once again in the future.
A tube station of the same name serves it, and it is here at Marble Arch station that you can pick up your car hire. Once you leave the station Marble Arch is pretty much the only thing you can see. It's huge, and does look a little out of place.
Some interesting points about the place include the fact that it is nearby the largest Marks and Spencer department store in the country. It also used to house London's largest cinema screen. Perhaps more gruesomely, but no less historical, is the fact that the area is near to the site of the old Tyburn Gallows, a place where, until 1793, people were hung.