Raschpëtzer is an artifical aqueduct (qanat) from Roman times, consisting of about 35 wells dug into the rock and linked together by a 600 m main passage and a net of secondary passages, designed to capture the underground water and take it to Roman villas.
Raschpëtzer is a particularly well preserved example of a qanat and is probably the most extensive system of its kind north of the Alps. It has been under systematic excavation for the past 40 years. It was built during the Gallo-Roman period, probably around the year 150 and functioned for about 120 years thereafter.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.