aqueduct

An artificial channel that is constructed to convey water from one location to another.

A structure carrying water over a river or depression, especially an ancient structure.

All the years he’d been down there in the traffic he’d taken this aqueduct for just another bridge, nothing to tell you that canal boats and waterfowl were being carried along above your head.

A structure conveying fluid, such as the cerebral aqueduct or vestibular aqueduct.