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.
posted by bad grammar on Jan 19, 2010 - 46 comments

"Murder all journalists, I beg you!" That's just one of the strange phrases that have appeared on tiles embedded in roads in locations as diverse as Cleveland and South America. The tiles also contain cryptic phrases regarding Stanley Kubrick and English historian Arnold Toynbee. Strange stuff.
posted by hipnerd on Sep 9, 2003 - 17 comments

Invasion of the mall walkers? (NY Times) New Yorkers may well have seen this story about sidewalk etiquette on the front page of the metro section today, but I wonder 1) if other cities experience the same phenomenon and 2) if other New Yorkers have noticed this marked increase in sudden stoppers and other sidewalk amateurs.
posted by lackutrol on Jul 16, 2002 - 42 comments