Located in Juvisy-sur-Orge, the Camille Flammarion observatory bears the name of its founder, a French astronomer, writer, and climatology researcher. But the history of this residence, located in a large park, goes back much further, to when in 1730, the king's court slept there. In 1883, its owner at the time, a rich businessman from Bordeaux, bequeathed it to Camille Flammarion. On the impetus of this scientist, the property saw the addition of its 5-metre high cupola, with a refracting telescope, an extensive library, a meteorological laboratory, and a large sundial.

Upon his death, he left the observatory to the French astronomical society. It is now listed as a historical monument. The building is not open to visitors, but it is lovely to walk through the park in the footsteps of this friend of Gustave Eiffel. In this park one can find an oak tree that he planted at the beginning of the 20th century. The central pathway leads to the tomb of Camille Flammarion, topped with an authentic Egyptian Luxor obelisk.