The pavilion houses the International Bureau of Weights and Measures and that piece of platinum-iridium alloy is its holiest relic. The international metre convention was signed in 1875. It is only the kilo that has continued to be defined by a manufactured object, that lump of alloy in Paris. This metric system was put forward in 1791 with the kilo being defined in terms of the mass of a given volume of water at 0C. Eventually, the international metre convention was signed in 1875 by 17 nations.

Source: The Guardian November 03, 2018 15:00 UTC