Paris meridian

The Paris meridian is a line of longitude that runs through the Paris Observatory, located at sixty-one Avenue de l'Observatoire. Founded by Louis XIV in sixteen sixty-seven, the observatory was established specifically to house this meridian, which served for over two centuries as the reference point for French cartographers and sailors. Long before the Greenwich meridian became the international standard, French scientists used this line to calculate the size of the Earth, defining the meter as one ten-millionth of the distance from the equator to the North Pole along this precise arc.