Little windows into the past
January 19, 2010 5:18 PM Subscribe
If you live in a sufficiently old city in the U.S.,Canada, or the UK you've probably seen these set into concrete sidewalks or the panels of cast iron steps. Termed vault lights in the U.S., pavement lights in the UK, and sidewalk prisms in Canada, the glass insets were originally clear and intended to produce daylighting in subterranean spaces. The ethereal purple color results from the glass's manganese content being exposed to ultraviolet light over time. Many vault lights or sidewalk prisms are in poor condition, but some are being repaired.
This thread has been archived and is closed to new comments