Another picture that I found inspirational.
The brick-like walls of the tunnel bended in an arch. Three arched gateways open at its sides and another dark tunnel opened at the end. The fluorescent lights glowed a pale yellow and hung, ever so often, from the ceiling. The pasty walls were a moldy green-brown and looked as if water and bleach had seeped through the stone bricks. A small silver trashcan lay next to one of the tunnel’s portals. The smell of stagnant water added to the stuffy feeling of the tunnel. The wet stone felt slimy on my bare and clammy feet.