The public art installation Het Licht van Jan (Jan's light) is situated in an industrious underpass near Amsterdam's city center. Visitors walking by activate projections that illuminate the weathered walls and narrow sidewalk of the underpass.

Het Licht van Jan's projections are produced by a simple arrangement of bright lights and steel grates. The shadows of these grates combine into moiré-patterns, producing entirely different effects on both the wall and the floor. On the tile walls, beams of light move along with the pedestrians, while on the sidewalk, waves of light gently rock towards them.

The underpass is located on a historic site, where several natural and constructed bodies of water existed before the railway was constructed in the late 19th century. Het Light van Jan brings back this past by reviving both the flow of water on the ground as the sunlight radiating through the railway tracks on the walls.

Het Licht van Jan is named after Amsterdam's remarkable city councilor Jan Schaeffer, whose statements served as inspiration for realizing the artwork.