This is Notre-Dame in Paris,
one of the most famous sights in the city.
But I'm not here for the view from the top
or for the flying buttresses, or even for religion.
I'm here for something just outside it.
If you look down from the top and stand just outside the main entrance,
you will find a marker on the floor
called Point Zero.
Point Zero is the place from which all distances
in France are measured from.
Now, I'm filming all the way out here, by the way,
because once one person starts taking video of it,
it starts to attract tourists in the same way that
artisanal French bread attracts pigeons.
That's a visual metaphor for you there.
France isn't the only country with a Point Zero;
a lot of countries in the developed world have them.
There'll be a marker or a monument somewhere in the capital city
that says "this is where the numbering starts from".
The UK though...
...uh, no, we don't have one, neither does the US.
I mean, the UK does have Charing Cross in London,
but only some roads are measured from there.
And the US, well, you do have a marker in Washington, D.C.,
but, well, no one uses it for anything.
Most US states restart their numbering when a road enters their territory.
And, here in Paris, though, you have a marker that isn't really used anymore
in these days of GPS and satellites.
But what you have is a relic of a past time,
a marker that simply says "this is where we started from".
This is back when we had all the triangulation
and manual calculations needed to actually map something,
back when it was longhand.
This is where it all began.
That's Point Zero and that is something you might not have known.
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