Camille Flammarion Observatory, Astronomical observatory and historic monument in Juvisy-sur-Orge, France.

The Camille Flammarion Observatory occupies a former 1730 post house on Route nationale 7 in Juvisy-sur-Orge, its pale stone facade topped by a stone balustrade and a silver dome. A cylindrical crenellated tower with a conical roof stands at one corner, and a smaller turret projects from the wall. The arched entrance gate is inscribed OBSERVATORIUM, and the curved gable above carries a sundial and the motto AD VERITATEM PER SCIENTIAM.

The observatory was founded in 1883 by French astronomer Camille Flammarion, who converted a former postal relay station into a scientific research center. This transformation made the site a significant hub for astronomical work in the region.

The gateway bears the motto "AD VERITATEM PER SCIENTIAM", which Flammarion had inscribed when he moved in. The site is owned by the Société astronomique de France, which co-founded and still organises public observation evenings there. Flammarion died in his study on 3 June 1925; his grave, a column in the park, holds him between his two wives, Sylvie Pétiaux and Gabrielle Renaudot Flammarion.

The observatory stands on Route nationale 7, formerly avenue de la Cour de France, near Juvisy town centre on a hilltop plot with several buildings, a monumental gate, gardens and a small forest. The Société astronomique de France organises regular public observation evenings here. A tramway line 7 stop named Observatoire was planned close to the fragile listed building, a move that was debated.

Camille Flammarion is buried in the park beneath a column, flanked by his two wives, Sylvie Pétiaux and Gabrielle Renaudot Flammarion. The garden also holds a grotto and a kiosk, both showing their age, and century-old trees he planted himself.