Cobblestones

[TommyDobry]

How were the rectangular street paving stones made? They are so uniform in size and shape, about 4 or 5 inches thick and wide by about 8 or 10 inches long. There are millions of them paving streets in colonial sea port cities, supposedly used as ballast in sailing ships from England and Europe. I can't believe that they are natural but can't imaging millions being carved by hand either.

[Quizmonster]

Cobblestones were, by definition, water-created, just like beach-pebbles. I imagine they were collected from rivers and shorelines, on the basis of a uniformity of size, so that some assessment of their weight could be made. That may have been necessary when calculating the quantity of ballast required.
Having reached their destination, of course, they were replaced by goods of a similar weight for the return trip. Clearly, the authorities decided to put them to use as paving in the ports where they were piled up.

[ianess]

They are man-made but exactly how I'm not sure.  I can only surmise that it is done along the lines of brick or breeze block manufacture but using harder materials.
Click here for an interesting article.               

[sddsddean]

Standard size of a 'granite sett' is a 4" cube. They are now cut by machines in quarries, but still have the hand cut rough surfaces so they match with existing setts. If you ever lift any setts, don't throw them away. You can get about �4 or �5 for each used sett if they are in good condition.