Arbre de Hadrien et Camille

It appears there may be a misunderstanding regarding the name or location of the tree you are seeking. There is no historical or official landmark in Paris known as the Arbre de Hadrien et Camille. The name Hadrian is famously associated with a historic sycamore tree in northern England, which stood beside the ancient Roman defensive line known as Hadrian's Wall. That tree, often called the Sycamore Gap tree or the Robin Hood tree, became internationally famous for its dramatic silhouette before it was unlawfully cut down in late 2023. It is possible this name has been confused with a location in Paris or conflated with characters from popular media. Paris itself is home to many remarkable trees, such as the oldest robinia in the city located in Square Viviani, but none carry the title you have mentioned.