Well, SWMBO read The DaVinci Code (book) while we were in Paris, but that particular photo was for the Meridien Zero geocache. Arago was a frenchman who tried to establish Paris as the zeroeth meridian for time zones, and has a set of 139(?) of those brass markers laid in a N/S line as the reference.

But the Brits eventually took over in that field.

Cheers