A sign outside One Pancras Square in London indicates that travellers can access the Underground at this point. 

An escalator takes you down to this tunnel that runs beneath the building and connects to the Underground lines at King's Cross and St Pancras and the HS1 pedestrian tunnel.  Designed by Allies and Morrison it has as its main focus what they describe as a, "... 100m long light wall, a canvas for a variety of art and light displays to create a positive and warm impression."  They add that, "... Metal canopies shaped as ‘mini-auditoria’ are arrayed as repeating units of construction around a constant radius. Louvred fin sections serve as a visual baffle for services, with openable sections providing full accessibility for future proofing. The flooring comprises two shades of ceramic grey tile, which creates a subtle zig zag texture responding to the module of the tunnel components."

Spiers and Major were commissioned to come up with a way to enhance the tunnel through lighting.  Their idea was to create, ".. a memorable and immersive experience, to create impact and mark it out as one of the main gateways to the site. We visualised an illuminated graphic artwork, running the full length of the tunnel, activating the dramatic triangular cladding and drawing pedestrians from the adjacent Tube tunnels.  The resulting wall provides a soft, seamless light effect, with the ability to produce both beautiful pastel shades as well as intense, saturated colour; all of which can be gently animated. The design was developed in close collaboration with The Light Lab, who also manufactured and installed the feature."

Light Lab, "... designed, manufactured & installed the seamlessly jointed glass wall, backlit with LEDs capable of emitting the full RGB spectrum & a white light spectrum from 3.0K to 6.0K. This provides a continuous curved appearance, with no shadow lines throughout."  They add on their website that, "... The art wall concept was originally conceived by Speirs & Major, with the artwork  created by Cross Kings & Tom Sloane Design. Creating lighting in stunning muted pastels, so that the feeling of walking through the tunnel is not a harsh, neon experience, but rather works very subtley alongside the pedestrian, to create a soothing, relaxing journey."