Thursday, January 7, 2010

Blue Cobblestones

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.


  1. The original use of the cobblestones was as ballast in ships taking gold bullion bars from the New World to Spain. It stands to reason that, once the gold was exhausted, they likely were used in sugar-carrying ships.

    1. A beautiful story but it's not true! There were ordered by San Juan and paid for from Liverpool from the brothers Sutherland. May , certified tourguide

    2. Thank you, May! What is the name of your tour company?

  2. I'm getting a bit confused. I just read somewhere else that cobblestones are really riverbed stones smoothed and rounded by the flow of water and come in naturally different shapes and sizes. They were used to pave streets, in their original shape.
    I also read that ship ballasts were slag, the by-product of ironworks factories that were cut into bricks to easily load as ballast. So, I surmise that the "cobblestones" in San Juan, Puerto Rico are really bricks or pavers. Yet,
    landscapers and lots of others refer to man-made bricks as cobblestone.
    Also, I find it strange that someone thinks that the slag bricks were used as ballast at the same time heavy gold was being shipped. Wasn't ballast used when ships were fairly empty?

  3. I have 1 blue cobblestone from a street in San Juan. My wife and I went there on our honeymoon. I did not get it at that time, however I did try, lol. A man that I met a few years later told me that he live in San Juan and he would get me one... I, of course, thought he was full of it! 6 weeks later, he handed me an actual paver from the street he lives on! I was completely BLOWN AWAY!!! I stare at it every night and wonder where the hell can I get more? It's not flashy or fancy and it's faded and chipped and still has "mortar" on it.... I want more of this beautiful stone! He can't bring me what I want, lol, but I want more......

  4. It may be "cool" to have a piece of Puerto Rican history, but it takes away from many others enjoying it and appreciating its antiquity in the original location. Whether you paid for it or not, that encourages others to steal pieces of their country's (or commonwealth's) "life", slowly chipping away at its past. That is sad. And now with Puerto Rico trying to recover from the massive devastation caused by Hurricanes Irma and Maria, they need all the help they can get.