The Vanne aqueduct: built between 1867 and 1874, it is 173 km long, and still supplies the city of Paris with drinking water. The water inside circulates by gravity alone, the high source being at 111 m altitude, whereas the Montsouris
reservoir at the end is at 80 m. The slope is not always regular and sometimes requires special facilities, such as siphons.

Bouldering in Fontainebleau: the forest of Fontainebleau is a world highlight for bouldering. To-day more than 30,000 boulders are open and secured in the forest for the practice of rock climbing. There are circuits of various difficulty
(color-coded from white to black). On this trail, white marks signal a bouldering circuit for children, who can also play among the rocks at the foot of the Rocher du Télégraphe.