The wrong rocks

Writers stretching to limn some scene as quaint or antique will almost invariably refer to the place's cobblestone streets. Much of the time they will be wrong. 
Cobblestones are rounded and irregular in size, typically rocks worn smooth in rivers. Riding over them in a wheeled vehicle is a jolting experience.
What writers mistakenly refer to as cobblestones are more commonly paving stones, particularly Belgian blocks, rectangular in shape, usually shaped from granite. They are also called setts
If you doubt me (and why should you? Have I ever steered you wrong?), Mark Dominus of The Universe of Discourse has published photos of each type. Many thanks to Jesse Sheidlower for the tweet alerting me to his site.