Masonry Magazine February 2003 Page. 29
A Brief History of Segmental Retaining Walls
"I noticed, especially on the street where I lived, that the municipality used to tear down and put back up, almost every second year, some rubble walls," recalls Angelo Risi.
"Sometimes they would use broken pieces of sidewalk stacked up. With the frost we have in Canada, invariably the wall would start moving around and in a couple of years they would be rebuilding it again. I thought to myself, 'My uncle is in the business, and if he could build something that would lock itself into place, that would solve the problem of constantly rebuilding these walls.'"
We came up with the idea of basically a slab with a broken face and a tongue and groove to it so that they would lock into each other. We tried it—we called it Pisa Stone after the Leaning Tower in Italy—and I was able to get a patent on it.