[aftbit]

More about that piece of platinum in Paris, the International Prototype Kilogram (IPK): https://en.wikipedia.org/wiki/Kilogram#International_prototy...

Also, something I had never heard of, Vienna Standard Mean Ocean Water: https://en.wikipedia.org/wiki/Vienna_Standard_Mean_Ocean_Wat...

[bambax]

It's not in Paris but in Sèvres, 10 km west of Paris (where I live).

[knodi123]

The most precise reference for a kilogram in the whole world? It's approximately in Paris, more or less- we care about precise weights, not precise locations. /s