A pretty little side street in San Juan, Puerto Rico. The blue cobblestones are beautiful. Here’s a little bit about them. I must say considering they are so old and the treatment they get now with cars going over them constantly, they are holding up amazingly well!
“The sometimes steeply sloping streets of Old San Juan are paved with blue cobblestones. Rather than being cut from stone or cast as bricks, as was the usual practice, the cobblestones found in Old San Juan are an ingenious re-use of slag from Spain’s iron foundries. Slag is the waste when iron is refined and was usually just piled into huge slagheaps at foundries. But cast into blocks, the material served as ballast in sugar-carrying ships in the 16th century, and this 500 year old recycling effort produced a durable material for paving the streets of Old San Juan. The Spanish word for these pavers is “adoquines,” and most of the streets in Old San Juan are still paved in this material.”