Scotch House
Junction of Knightsbridge, [Sloane Street]? and [Brompton Road]? in Brompton. Better known as home to Knightsbridge station on the Piccadilly line.
This is part of the A4, a main route into London... so it's extremely busy! This is one of the pinch points, and all traffic is slow through here throughout most of the day - so it's best to avoid it if you can, and if you're in a hurry.
The junction layout is rather odd, to try to stop traffic blocking it - so if you are turning right from Sloane Street onto Knightsbridge for example, you turn left first, and then follow a circuitous U-turn route to go back the other way.
If you're unfamiliar with the junction, follow a bus. All double-decker buses go to or from Hyde Park Corner (not much use if you're going a different way, but it might help!).