English to French Other Engineering (general)

All this remains invisible from the entrance of the fort, because the museum is buried in the hill and has no exterior façades, its entrance hidden in the back wall of an old barracks building. But when one climbs the grassy roof landscape and sees it from above, the layout of the Waterline Museum suddenly becomes clear.

Toutefois, lorsque l'on voit/découvre tout cela à travers le paysage de toitures herbeuses ?