Le Maregraphe

The Maregraphe sits inside a small, white stone building directly at the water’s edge in Marseille. It holds a brass cylinder containing a continuous roll of graph paper, marked by a pen attached to a floating buoy in the sea. Since eighteen eighty-five, this device has tracked the rise and fall of the Mediterranean tides. It served as the singular reference point for all altitude measurements across France, defining what zero elevation means for the entire country.