I've heard rumors that the recipe for Cobblestones has been lost. Here in Indiana, they used to be cast at a factory in Attica[2], I have a pile of them from an old walkway we've replaced. The embossed lettering is proof they aren't carved or cut, but rather cast with a debossed negative mold.

I was surprised to learn that most cobblestone was actually quarried rectangular blocks[1], used as ships ballast, discarded after cross-Atlantic voyages.

[1] https://en.wikipedia.org/wiki/Sett_(paving)

[2] https://indianaalbum.pastperfectonline.com/photo/5FA11838-DE...