In addition to its unusual position, the construction, which was originally thought to be a three-story structure, shows more unique features such as a control corridor below the water line, as well as explicit private funding.

One end of the 6 km long pipeline opened onto a 200 hectare farm situated in west Aosta, 50 to 150 m above the main river Dora Baltea using a gradient line from the neighbouring valley.

The water from the Grand Eyvia, which is diverted 2.9 km above the Pont d’Aël, was directed downhill onto the steep slopes of the Cogne valley in open channels with an average gradient of 6.6 per mille.

On both sides of this 3.88-meter-high (12.7 ft) control corridor there are two rows of small windows from which the lower floor and the upper ceiling are illuminated so that the bridge keeper could quickly identify leaking water, which could have damaged the stonework with frost.

Döring was able to prove beyond reasonable doubt the existence of the ancient aqueduct, where the trail runs today, on the basis of the altitude and course of the preserved remains of the walls, as well as a subsequent tunnel west of the bridge.

At the time the third floor was possibly an open walkway, which gave the building a total height of 22.15 m. Completed: Translated: Media related to Pont d'Aël at Wikimedia Commons