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Origin and history

The meridian of Orveau-Bellesauve, also known as the astronomical obelisk, is a memorial erected in the village of Orveau-Bellesauve in the Loiret department (Centre-Val de Loire region). Located on the route of the meridian of Paris, it takes the form of a 7-metre-high stone obelisk, placed on a parallelepipedic base and surmounted by a sphere ended with a pick iron. Its faces are oriented according to the four cardinal points, and a medallion on the south face bears the inscription: "Meridian of the Observatory – Scale 541 toise 2 foot MDCCXLVIII". This building, dated 1748, is part of a network of about a hundred obelisks commissioned by César-François Cassini to materialize the meridian of Paris, as part of the cartographic work that led to the famous map of Cassini.

The construction of the meridian is part of a large scientific undertaking carried out in the 18th century by French astronomers, including Cassini and Nicolas Louis de Lacaille. Their aim was to refine the measurement of the meridian of Paris, a major geographical reference for the time. The obelisk of Orveau-Bellesauve, erected under the reign of Louis XV, symbolizes this ambition. During the French Revolution, the flower of lilies that initially overcame it was replaced by a prick iron, reflecting the political upheavals of the time. Today, it is one of the only three remaining obelisks of this project, along with those of Manchecourt and Paris (mire of the North), bearing witness to the scientific heritage of the Enlightenment century.

Ranked a historic monument on 16 September 1916, the obelisk of Orveau-Bellesauve is distinguished by its precise location: to the northeast of the village, on the lower side of the road leading to Gollainville. Only 4.65 km south is the Meridian of Manchecourt, a similar milestone, highlighting the density of the original marking. The inscription engraved on the medallion, mentioning "541 toise 2 foot", recalls the units of measurement used at the time and the precision scale targeted by astronomers. This monument, both scientific and heritage, illustrates the alliance between technical knowledge and historical commemoration under the Old Regime.

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