Artificial lighting in Clink Street Tunnel on London's south bank.

If you search the internet for Clink Street Tunnel you'll find much more dramatic photos of the lighting under this tunnel (an old railway tunnel between Southwark Bridge and London Bridge). There is an installation of LED lights in the tunnel roof that is programmed to change according to the flow of pedestrians beneath it. When the flow is light, white LEDs twinkle like stars; when heavier there's a colourful firework-like display. It was the twinkling effect when we walked beneath it, but I chose in this photo to isolate one of the purple side-lights and the shape of the arch instead.

Camera/lens settings: ISO 400, f/6.3, 1/80s, 18mm, hand held.