Old San Juan - III

The narrow streets of Old San Juan, many of which are paved with blue-gray bricks. When trading ships used to come from Spain and Europe, they came with hulls full of these bricks, dropped off the bricks and picked up their cargo of sugar or other island products. The ships couldn't sail if they were empty, so they used these bricks for weight. Eventually San Juan accumulated so many bricks that they started using them to pave their streets!