A very nice discovery I made thanks to the 'Journées du Patrimoine' (Heritage Days): the aqueducts in the Meudon forest.
They used to provide the Meudon castle (which no longer exists today) with enough water for the gardens and the many water jets fountains that were displayed at that time.
The aqueducts have been cleaned up and maintained by a small association, and some of the elements can easily be seen while strolling in the forest!
Stone bridge over the aqueduct
Aqueduct channel below the bridge
Open-air water duct