Several prehistoric settlements and remains of a Roman road station have been discovered in Welschdörfli, the old town district in Chur. You can visit the excavations and discoveries on the Ackermann grounds on Seilerbahnweg.
The protective structures covering the archaeological sites from the Roman era were built in 1986 according to designs by local architect Peter Zumthor. They do not only protect the finds, they are also a museum and architectural masterpiece. The weighty building with its delicate rilled outer surface is reminiscent of the original Roman edifices.
You can get the key to the protective structures from the Chur Tourism information centre at the station.
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.