France's 1789 revolution has left France and the world with many legacies, including the metric system...but one measurement change has left behind only a few traces: the Revolutionary Calendar.
The months were given new names, reflecting seasonal weather and agricultural patterns; each month had 30 days, and each week 10. The 10-day weeks were abandoned in 1802, and the calendar in 1806.
But in the meantime, you can see the effect on the monument above, in Chartres, honoring the efforts of the local Prefect and Mayor on the First of Vendemiaire of the Year X, also described as the Second Year of the Consulate of Bonaparte. If you're curious, 23 Sept. 1801.