English: Sidewalk prism lights outside 440 West Pender Street, Vancouver, BC, from above, with lights shining up from inside the hollow sidewalk. View down onto a sidewalk with vault lights; a slab of concrete with a regular grid of inset squares of slightly domed purple glass. Within each square, faint vertical lines can be seen through the glass, and points of light shining up through the glass are duplicated in horizontal lines of three points of light. Some yellow leaves have fallen on the damp concrete.The purple shade has developed over a century of solarization. These are multi prisms; the ridges can be seen running vertically.