Street of Pompeii
To clean the streets, everyday they would flood them. These raised stones across the street were so pedestrians could still cross the road. Chariots could straddle them on both sides. You can see the ruts in the roads created by the wheels of chariots. The main street of Pompeii (not this one) was a pedestrian only street and had 3 large stones blocking chariots from entering at either end.