The French Revolution got rid of old things that didn’t make sense, like monarchs and backward-ass provincial measuring systems. It’s when the metric system was invented. Previously, units of measurement were derived by recording the distance from the king’s nose to the tip of his thumb, but after Louis XVI’s head became suddenly unavailable, this was difficult to do.
So in the 1790s, France’s Academy of Sciences came up with a new measuring standard called the metre, which was one ten-millionth of the distance from the North Pole to the equator.
Now that they had the meter, they needed a way to popularize it. The Academy commissioned a series of platinum-iridium bars that were all exactly one meter long, and somewhat presumptuously shipped them to various countries as a new standard.
Platinum-iridium bars aren’t cheap to make, and France needed a less expensive way to promote meters among their own citizenry. So sixteen marble blocks with precise meters inscribed in them were installed on the sides of buildings around the city of Paris. Brass protrusions at the ends allowed one to mark the ends of a stick that you could cut to length, and lines etched into the marble denoted decimeters and, on the far right, centimeters.
At one point there were sixteen of these mètre étalons, but today only two are left. They’re neat to see for historical purposes, but obviously there is no longer any need for them. The French have accomplished their mission and metric has won the day.
Today there are only three countries in the world that don’t use metric: Liberia, Myanmar, and the United States. And we are poorer for it.
https://www.core77.com/posts/79999/To-Promote-DIY-Metric-Rulers-in-the-18th-Century-Paris-Placed-Meter-Long-Marble-Blocks-on-Public-Buildings