I have enjoyed the non-slip nature of some of the bricks in Lynchburg, VA. These bricks seem to have been manufactured by Chilhowie Paving & Sidewalk Co. or perhaps Virginia Paving. A VERY quick search yielded no ancient design or utility patents. But they are non-slip? Why did the manufacturing stop? Too expensive? Not innocuous enough?
Bring back non-slip brick pavers!!
Update from 2016 in Barcelona, Spain. These type of paving stones are used all over the city. A selection of patterns is shown below.